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Outdoor Reset Savings
Does anyone have a spread sheet or program that has successfully determined the actual (or close proximity)savings of installing weather responsive controls on existing system?
I am surprised that Tekmar does not have a program availabe where you can plug in the cost of fuel and fuel used and get an approximation.
wheels
I am surprised that Tekmar does not have a program availabe where you can plug in the cost of fuel and fuel used and get an approximation.
wheels
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Comments
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I'd like to see this info too.It would/could sway someone opinoin on a new install too.0 -
It would take a LOT more than just cost of fuel and fuel used to get an approximation with any chance of accuracy better than "rules of thumb".
1) Standard deviation of normal daily temps from design temp during the heating season--LOTS of tables for North America, but not too difficult to make your own.
2) ACTUAL supply temperature required at design.
3) Transmission loss to include area of piping, current supply temp, level of insulation, temp in space, etc.
4) Full (unlimited) or partial (return temp protect) or system-side only (mixing) reset.
All this is above and beyond actually calcuating the reset curve that should/will be used based on the type of emission device(s).
Sounds to me like even with a good progam, you'd spend more time determining the program input than the cost of many? most? reset devices that are almost certain to save something...0 -
Red light stuff
Aaah, tables, reset curves, equations, thermodynamics stuff, it sounds like boundless fun... Actually, I've got an opinion that, sadly, does not require the bells and whistles of a flashy spreadsheet.
What does an outdoor reset do? It probes the outdoor and then anticipates what is going to happen by following some design curve. The advantage is two fold:
1) It allows for advance heating, which is useful with somewhat slow to react hydronics, and particularly with radiant floor heat. But this does not sound like it should save fuel, does it?
2) It allows for advance stopping. Again, since reaction times are long with hydronics, the advance call on the end of the cycle will prevent overheating. Without outdoor reset on a hot water system you are very likely to get overheating, specially in the spring and fall.
So, outdoor reset does not really produce a fuel savings inasmuch as it doesn't make your home heat more efficient, but, and this is big, it prevents the waste of fuel used up for overheating.
Now, is it possible to predict how much you can save on overheating by preventing it? Not really, because there is no limit to how much you can overheat. In other words, the savings could be limitless... heck, it could be so good, the gas company will write you a refund credit check every month.
Honestly, the only savings you'll see are those that come from what you could have otherwise wasted on overheating. In the long run, the control system pays for itself.
How do you sell this to the homeowner? Ask them if they really think it is important that the yellow light comes on before the red one at a traffic signal. Do they really think they could always stop their car within the road markings without the advance warning. Skid marks at intersections prove to me that overshoot happens and so does overheating, it is a good thing to prevent. And there is more, the outdoor reset gives you an advance signal on when the light will turn green so you can rev up your engine, take off without delay and be warm and toasty for breakfast.
An alternative: grossly undersize your boiler, it will be the equivalent of never driving faster than 3 miles per hour. You'll never have to worry about your timing at red lights, but you won't get far either. Conversely, this means that the more oversized your boiler is, the more useful the outdoor reset becomes. Beyond some size it even becomes necessary.
And a few more thoughts for the owner.
Don't forget the comfort factor. Outdoor reset is vital in order to provide a warm house in the morning and to prevent the afternoon heat wave, that is nice, isn't it? But do you know what is even nicer? No? Shhh, I'll tell you a secret:
Steam heat!
I hope this helps and I hope you're all having bucket loads of fun.
Christian Egli
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But what about steam efficiency?
Seem like steam heat is a unique and comfortable way to heat, lots of fun tech involved. I'm glad to see the diehard steam guys hear carrying on this dying art, at least in the residential sector. Process steam excepted, of course.
But taking water through a phase change at 212°F plus temperatures doesn't seem very efficient when the same structure could be heated with 112°F water in a radiant floor or ceiling system?? That's a 100° spread in required temperature!
Considering also current tech allows this 112°F supply fluid, for a radiant system, to be generated at 90% plus efficiency
Not to forget the ease of solar tie in. Which seems awkard with steam
The beauty of outdoor reset, when combined with indoor feed back, as it should be, is it allows the lowest possible fluid temperatures to meet the demand at a given outdoor temperature. This is where I feel the savings, combined with comfort, shines through.
hot rod
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What about same type homes
in the same neighborhood , similar family size , with the same heating system , but one home had outdoor reset ? There are literally thousands of homes around here that are that meet the requirement , but sadly , I have never seen an outdoor reset control .
I realize you could sell the control system on the comfort factor alone , but I know poeple would want some numbers of fuel savings too - nothing exact , just some averages .0 -
But it only takes
a little bit of water to steam heat the radiators .
A typical water boiler holds a few more gallons than a steam boiler , plus the water in the system piping . Even if you only need temps in the 112 range , doesn't heating that extra water factor in ?
Another question - would a system with 18psi pressure take longer to heat up than a system under no pressure ?
As you can tell I'm no expert at this stuff , but with insulated mains and returns and a properly sized and piped boiler , I bet the total efficiencies between a conventional steam and hot water boiler get closer than you might think . Just a guess though .0 -
Documented reduction in fuel usage
HR, I have two customers who are tracking actual fuel usage by degree day to compare savings. Both now have a condensing boiler that modulates and utilizes outdoor/indoor reset to determine Btu output. One had been HW with a standard eff boiler without outdoor reset & the other used to be a two-pipe steam system. Both have witnessed a dramatic reduction in fuel usage - 30% and 70%. I haven't verified either one personally, but both owners are savy engineer types & have no reason to fudge the facts.
The 2-pipe steam system conversion was decided upon by the homeowner because he wanted some radiant and zoning plus a bit of hydro air to offset a missing radiator (ducted AC granted use of a hydro coil). The great room with the missing rad was set up with a 2-stage stat to activate the hydro coil only when the lone rad can't keep up.
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my buddy get the call...we wanna dry r gypcrete faster!
it is about 90-100¡ãF these days ,so i figure constant circulation no heat alls good. no we need a control on it ok...so the 361 is lashed up and my buddy gets another call. it aint working! WWSD figures its warmenough:) so day before yesterday th eyoung guy who hangs wit me dashes over and turns the reset to 90 ...get another call it aint 90 comming outa the slabs:) so last night when we got off work we go over there and re ajudicate the advanced settings to # that are within the paramaters although i would reccommend GC's jot to get the job done ....how i usually roll is to tell them their slabs have a 28 day waiting period and to stay off the slab for 8 days:) where are you guys at with this? 0 -
I'm with hot rod here
The "planning ahead" feature of outdoor reset is very nice, without a doubt, but it is the dynamic ability of a reset system to lower its water temperatures well below design maximums on a continual basis that really makes reset a great way to go, for a whole lot of reasons.
_______________________________
Northeast Radiant Technology, LLC
Robert Brown, Co-Owner, RPA certified Radiant Designer
207.899.2328
NRT@maine.rr.com0 -
it's not the heat, Weez
you need to get all that water out of a gyp, then out of the building! It's more of a humidity/ moisture game If your weather is humid the pour will not give up it's water as quickly as a dry day.
Ventilation is what you need more that heat. Get some large fans, and leave the boiler off
hot rod
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And Ron
I'm far from a steam expert.
Lets say both a steam and radiant system start up on a cold fall day. Both have water at 65° in them.
Not knowing much about steam boilers could an average boiler contain 20- 30 gallons of water? Small to mid sized radiant would be in that 30-40 gallon range, total system capacity.
It takes one BTU to raise one pound of water one degree F.
If both contain the same amount of water certainly the lower temperature system would require less BTUs to get to speed. Of course the steam contains more heat at the higher temperatures, also.
I think the biggest factor would be pipe insulation in a steam system. If pipes running through 65° basements or crawl spaces are un, or poorly, insulated the larger the delta t the greater the loss to the surrounding space.
Again that 100° difference between steam and radiant supply temperature would drive that piping loss, in a big way.
Could you pipe a steam system with pex? The lowest possible water temperature to heat a space makes a lot of sense to me.
]As Mike mentioned there are a lot of efficiencies involved in a heating system. Within the boiler itself you have combustion efficiency, measured by CO2 and temperature at the exhaust.
Then cycle efficiency defined as the ratio of total heat output divided by the chemical energy value of that fuel. Also steady state efficiency, continous non vary load and operation so heat output divided by energy input.
All these are optimuized in modulating condensing equipment on reset controls. As the boiler, properly sized, runs steady state non stop. It supplies only the temperature of water needed for the loss of the building. And it does so with flue gas exhaust temperature a few degrees above the temperature of the heating supply water temperature. Hense the 90% efficiencies. I recon a steam boiler could have flue gas temperatures in the 400°F range. That's a lot of wasted energy up the flue!
It is possible for a wide modulating boiler to fire in the fall and never shut down, it just constantly adjusts it burner firing to the buildings heat loss. As long as there is a heat demand, of course. What a concept for reducing cycle wear on gas valves, vent motors, circ pumps, relays, etc, etc.
That's a hard package to improve on
Of course the building efficiency is the mother of all loss calcs.
PAH's example will be a pretty telling example. I would like to hear that data after a few heating seasons. A before and after picture of the exact same home with the same living use. Hard to argue with the actual calculatable dollars saved over a wide time frame.
hot rod
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surface humidity
Weez,
I'm far from a concrete expert, but I remember reading about how they built hoover dam. They plumbed cold water pipes into the concrete boxes that they poured, so they could pull the heat created by the chemical reaction out of the concrete and allow it to strengthen with larger pours. Of course, they were dealing with much larger amounts of concrete and it wouldn't be a problem with a thin slab.
So the relative humidity and the air flow across the slab will control how quickly it loses the water.
Just to point out the obvious, the faster the concrete cures, the weaker it is. I don't have any numbers, but he may be getting into an area where there isn't sufficient strength to accept and hold fasteners.
When they want to go faster in major construction projects, they will generally increase the concrete strength from run of the mill 2500-3000 psi to 5000-7000 psi and then start building on top of it as soon as it has reached the needed strength. When loan interest is a big deal, this can be a real savings. I would much rather see people do this than weaken that 2500psi stuff down.
jerry
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wellp:) So today i go back to check. the psychic police turned all the windows closed! whats a guy ta do:) ok so all the windows are open again cranked the supply side up to 123...the teck mar is controling the thermostats and thats about it closed the end switch on boiler cranked the variable speed (Injector) and system pump on full time direct ...good thing the slabs had a couple weeks and three days before it saw this type of treatment:)usually i roll 50ish water through then a few more degrees each day After the 28 day waiting period.i get all the air i can out of the system hurray for spirovents after that:) then in about 4 days time i crank on the boiler and ajudicate everything from there. i am happy with that meat head meathod of mine because i understand how that works:) snapping heat to it after 17 days i just dont know the long term deal...floating tarkett and floating laminated false wood will be headed on to the thing in the next couple days. luckily the tarkett installer Knows his stuff and the moisture level at which to install...Hurray! i know it will be time to dial it back down soon:) oh the crawlspace(insulated perimiter )has no insulation in the floor yet under the gypcrete..the ground is less than 60 degrees...so which way is the heat gonna go anyway guys:) out to the surrounding 90+¡ã space or down to the ground under the crawl space?:) ok good thinking:) 0 -
your own experiment....
lotsa variables,could try using a line voltage thermostat located outside, with a 2 $ clock hooked to the burner power....set it on 65 and leave it for a year,take the recordings once a day for a year run time...then do the same for another year:) write your own program:)0 -
it's like religion
As you can see from the above, outdoor reset is not a matter of numbers. It is a matter of faith. "Blessed are they who have not seen but have believed."
There are two ways of selling outdoor reset and you have seen both in the above. One is to give logical-sounding arguments "It must save money because..." But that proves nothing. Logic so,etimes works and sometimes doesnt, it works best after the expt has been done and shown what the actual situation is.
The other is to say "My client saved x%." This is called anecdotal evidence, and it is not rigorous or meaningful, because they made other changes including getting a better boiler. You are expected to believe that some large part of that 30% or 70% is due to outdoor reset but no one knows.
Really, there is NO scientifically valid evidence. It is all snake oil.0 -
dear flame baiter
I would suppose you can also dismiss lab studies already done as well as large scale studies such as the ones being done by Oak Ridge Labs and Habitat for Humanity as well. And god forbid you would ever look at physics and computer models, those must be snake oil. You can always dismiss information rather than trying to learn something.
The most difficult part of estimating the real world gain from a condensing boiler is because it's part of a building system. Most smart people also invest money elsewhere to reduce energy demand, such as improved insulation, better sealing and/or different emitters. Then it is hard to say that the boiler contributed x% to the overall drop in demand. It is also difficult to factor in things such as adjusting the demand up to give better comfort with an affordable fuel bill.
Given that almost none of the systems have any form of data collection other than meter readings before the upgrade and few collect much more than that afterwards, I would doubt you would ever be able to find a real world before and after example that would bear much scientific scrutiny.
This is a topic near and dear to my heart. I am investing quite alot of time and effort in at least being able to do full data collection on my project. Sorry, there will be no before numbers so it will still be snake oil to you. I will at least be able to provide a case study for demand and heat for those meaningless computer models.
You can crawl under your rock again now!
jerry
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A typical sized
new residential steamer holds around 10 to 15 gallons .
Thanks for taking the time to explain it out . Even though I never get my hands on high efficiency , modulating equipment hooked into radiant zones , I can understand how fuel can be saved compared to a conventional steam system . I was basing my opinion on conventional hot water and steam boilers , where I think efficiencies get closer together .
The big question is if the added cost ( and presumably , added maintenance ) to a high efficiency system is worth it for the homeowner .0 -
In most cases, yes
In most cases you're talking about an additional few hundred dollars in initial costs to go full outdoor reset and indoor feedback. Outdoor reset only isn't that much more at all.
Ignoring all the comfort and precision benefits for a moment, if that saves only 10% in efficiency savings, it'll pay itself back relatively quickly, then you start saving money, and you have a better system to boot for all the non-efficiency benefits of comfort, hardwood floor protection, etc.
Obviously in very low-loss homes this may or may not be as important.
_______________________________
Northeast Radiant Technology, LLC
Robert Brown, Co-Owner, RPA certified Radiant Designer
207.899.2328
NRT@maine.rr.com0 -
Do you believe cruise controls
save gas when used in your vehicle? If so, outdoor reset is a similar, understandable, concept when explained to the homeowner this way.
hot rod
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Tell me if I make sense or if I'm just long winded.
You know, your arguments sound like an "I clobber you the head" proof, it hurts.
Now that you've got my blood boiling here is the way I look at the situation. So, we have a given fire that's going and now, our goal is to remove from it as much heat as we can. We'll then use the heat for heating, isn't that what both boilers and furnaces do? One good way of knowing how much heat was removed from the fire is to measure the exhaust gas temperature. The colder the better, no?
Well, I've long been in the habit of sticking my thermometer where I probably shouldn't, but I have consistently discovered that hot air furnaces always had the hottest gas, while boilers and hot water heaters had much cooler gases (note that I am not including condensing systems in this comparison). Generally, steam and hot water boilers produce the same temperature gas but properly operating steam boilers seem to make cooler smoke compared to similar boilers on hot water. This evidence is anecdotal, of course, but I am looking for something that makes plain common sense.
If flue gas temperature was strictly related to the temperature of the heating fluid, it would follow that steam should always be the looser and forced air furnaces should always be the winner, and that's clearly not what I have seen. So, there must be more to the story.
Boilers and furnaces are built about the same way. There is a fire on one side with flames licking the surface of a heat exchanger made of steel or cast iron (and there is no big difference between the thermal properties of these two metals, in comparison copper would be fantastic and stainless steel very very poor). The surface of these heat exchangers is related to the size of the fire and are all proportionally similar. The proportion is also linked to cost factors where smaller is cheaper, but what I am getting at is that for any type of system the time you've got to extract the heat from the flame and the smoke is very short and is limited to the flue gas travel time within the innards of your furnace, boiler, or hot water heater. You'll agree that the travel time for all these are roughly similar, and identical for either a steam or hydronic boiler. Zip, and the smoke is gone up the chimney. We are in the business of heating the birds!
What happens next? How much heat and how fast can it be taken away from the other side of the heating surface? Here we have many choices. We can use air, water or steam and here is where steam shines and air stinks to no end. Steam is a workhorse and can load about a 1000 BTU per pound (1151 BTU/lb at 212F) while water at 112F, warmed up by the standard 20F will carry an all but whooping 20 BTU/lb, it seems embarrassing (water at 180F, even with a delta T of 100F would carry only 100 BTU/lb, not much better). How about air? well with a temperature increase of roughly 100F (this is high) it is rated at 25 BTU/lb and think of how much air you need to blow to get a pound of the stuff. That's where the efficiency of steam comes form, you don't need to be busy shuffling the stuff around, you don't need to yell at it to make it work faster. You just sit back in amazement and watch it dig into the heat. There is just nothing left to go up the flue, which explains the low stack temperature.
You've really got to work quick with both water and air if you want to keep up with the flue gas, and if you are too slow, you miss your only opportunity at catching the heat from the fire. Heat carrying capacities in all three can be increased by using a fan for air, a circulator for water and a vacuumizer for steam, these help by removing the heated fluid form near the fire faster than they would otherwise leave. It's a speed race to get the heat out and the winner is the one who can do it either faster or with the biggest payload. Number one on both points: steam, number two: water, last: air. That's why I root for steam.
Of course, the help we provide comes at a cost. It takes electricity (and quite a bit of it) to keep water and air moving. It generally makes sense to do so, because no one installs neither gravity hot air nor gravity hot water anymore, but who thinks of adding the electric cost into the overall efficiencies? And who remembers that steam more often than not provides its own mode of transportation, on top of the deal!
Isn't that great? Are we still friends?
On the issues of control, such as outdoor reset and programmable thermostats, all these are adaptable to any system and have more to do with the building heat loss and occupancy than the heating medium, but radiant heat seems to benefit the most from these schemes, and the comfort is optimal.
To just say a quick word about rated efficiencies on boilers, nothing has really changed a lot from the old 80%. Claiming that getting rid of the standing pilot light saves a lot of energy is true, but it does not in any way make the exchange of heat within the boiler any more efficient, and yet these claims always improve rated efficiencies. The thing with newer condensing boilers is that they capture new heat from the moisture in the flue gas, this energy is added to the efficiency rating, but once again it did not have much to do with making the exchange of heat more efficient. Don't get me wrong, the bonus is well worth getting but to pass judgment on old boilers based on this fact alone is a bit twisted. Take your same old boiler, add an extra heat exchanger in the flue, a condensing economizer, and you improve your old "rating" the exact same way, nothing new.
Do I smell marketing ploys, for sure, and that's the way the world goes, but I wish more of the same spin was done on behalf of steam replacement boilers. There is no reason why it couldn't. There is a vast hot air conspiracy going on out there...
I hope you enjoyed reading this. Thanks for stimulating my imagination. I think we are following the spirit of this website since I agree with you that steam is just plain fun.
Go steam go!
Christian Egli
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Who needs outdoor reset? Just get steam...
You're right on, Ron,
There is a big difference between steam and hot water as far as boiler content goes. In the steam boiler, the water stays there until it evaporates and it is renewed only very slowly, while in a hot water boiler, the circulator is constantly whisking those gallons away. After a minute, how much of the original water will still be there? Probably none.
A 100,000 BTU/H boiler on hot water with a 20 degrees temperature rise demands 10 gallons per minute, that's 600 gallons per hour, the same boiler on steam needs to boil away only 12 gallons per hour, that's fifty times less.
So, for a water system, the warm up time has to include the total water in the whole system, for steam, well, there is no other water than the one in the boiler.
The time to heat one boiler load of water only is more or less identical in both cases, it only takes a few minutes.
Once the water is boiling, it's a round of steam for every radiator in the house. This goes real quick, steam is designed to travel at speeds like 25 miles per hour! How big exactly is your house?
Hot water travels quick too, but the warm up time is slower because you have to bring the system contents up to heat, the total content is many times the boiler content. If we assume it is five times the boiler content, then it follows that a hot water system will warm up in fives times the time it takes for steam, maybe a little less allowing for the lower water temperature.
For the 18 PSI question, here is what I think. First off, why on earth would you need 18 PSI, if it is only to overcome the friction loss of a standard house, which is on the order of 1/2 a PSI? Your home would be hot as soon as the boiler had built up the first 1/2 PSI, then, with that achievement under the belt it could leisurely build the remainder of the pressure but the house would already be hot.
How long would it take? well, I am reading from a steam table, it takes 1151 BTU per pound of water to build steam at 0 PSI, that is at atmospheric pressure. To make the same amount of steam at 18 PSI we need 1166 BTU per pound. The difference between 1151 and 1166 represents an increase of 1.3 %. It does not take a lot of energy to build up pressure with steam (but if you don't need it, it is still a waste). The time it would take depends on how big your system volume is, it's like inflating a tire, it takes a certain amount of time. At 18 PSI you have a squeezed in a bit than double the atmospheric pressure, so it's like filling your system twice and the second time is slower than the first. If you closed the boiler steam valve, your pressure would rise frighteningly fast.
Hey, it is nice talking to you, and gosh, I am long winded.
Thanks for reading,
Christian Egli
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And there I go again
Thanks Dave for sharing the data from your two customers. I think this sort of evidence is invaluable, it always makes me think.
It seems obvious that the work you performed made sense in view of the impressive results. 30% savings for an outdoor reset seems like an achievable claim. Everybody is happy and that's what counts, but...
Do you think you could have convinced customer number 2 to keep his steam system, fix it up and get it running as good as it should? It would probably have been easier, and would almost certainly have yielded fuel savings of 100%.
From other posts, it is not unusual to hear that bills are cut in half once a system is restored to the way it should be.
How old was system number 2? I find it odd that people should expect, say, an 80 year old original system (that also has been neglected) to operate just as efficiently than a newest system on the bloc, and if not, to qualify it for the scrap yard. To me, the fact that the thing still works after all that time warrants a second look. Maybe just a little tune up will get it back up to peak efficiency and going for another 80 years.
Steam just keeps going and going.
Thanks,
Christian Egli
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HR - take that one step farther!
Nice analogy pard.
Cruise control vs bang/bang.
Typical boiler control would be like flooring the gas pedal every time acceleration (btu's) is required. No feathering or modulation - just a flat-out approach with no governor to limit speed. Overshooting the mark is expected (as in overshooting required boiler water temperatures - as in - wasted Btu's)
Outdoor reset would still be a bang/bang approach, just without the overshooting - kind of like having a governor to prevent over-revving the engine.
Now, add modulation to that picture and you've added a chauffer to the cruise control.
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Yes, that is a BIG question
certainly if the high efficiency equipment breaks down or requires lots of maintenance, the savings and return on investment goes down.
Like most new technology, it will take time to be able to answer those questions. we are already in that learning curve period with some brands
As I understand it oil fired equipment should have a yearly check, possibly cleaning, filter, and burner adjustment.
I feel the same yearly time should be spent on the high efficiency equipment to assure it's condition (water side especially) as well as burner check and adjustment. So that service call would be a wash between basic oil fired compared to high efficiency, be it gas or oil fired.
It's the longevity and breakdowns and associated costs of repair that will throw the wrench, or wench, in the works IMO
hot rod
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The 18 psi
I was quoting would be on a hot water system . I meant to compare how long it takes to heat a boiler with no pressure ( steam ) to a boiler with 18 psi ( water ) . I agree there is no need to run a steam boiler higher than ounces in most cases .
Which brings up another question - say a water boiler holds 10 gallons at 0 psi . How much more water does it take to increase it to normal operating pressure ?
You bring up very good points . In another post you mentioned that steam needs far fewer moving components than it's hot water counterpart - something I never considered till now . Keep the info flowing Chritian , love to hear it .0 -
Allow me a different approach
I think of outdoor reset as part of the feedback loop a PID circuit that tries to maintain an even temperature inside the home, regardless of how exterior conditions are changing.
Particularly with high-mass systems like radiant floor heat, it is awfully easy to "overshoot" once conditions outside warm up. Then, the only "control strategy" for the inhabitants inside is either to open the windows or to roast (slowly). A well-adjusted feedback-loop will account for the indoor thermal mass, heat losses at different temperature differentials, and the rate of change with respect to interior and exterior temps in order to come close to maintaining an even indoor temperature.
However, no matter what, the system is constrained by simple physics. On most residential applications, it is not an option to send cold water into the radiant loops to help cool the place down. That is, the best the system can do if the desired interior temperature is overshot is to stop firing and wait for the heat to dissipate over time.
This is why anticipating future heat loss is so important - a simple on-off Thermostat inside the place will never figure that out, no matter how well you place it.
Even at steady heat-loss, an on-off thermostat will never maintain as even an interior temperature as a PID controlled outdoor reset-enabled heating system will. The room temperature with an on-off system with a slow response like radiant floor heat will look like a sinusoidal wave, over and under-shooting the control limits as the system struggles to maintain the indoor temperature.
In contrast, a properly set-up PID controlled system will usually have a much flatter response as the system matches the heat input into the space with the heat lost out of it. Thus, it will start tapering off the heat as it approaches the setpoint from below and start applying bursts of heat as it senses approaching the setpoint from above. BTW, this is also the whole point of modulating a boiler, matching input with heat loss.
I think a cruise-control analogy is not quite right simply because the cruise control is not anticipating hills, etc. ahead. Instead, it simply looks for variability within the velocity hysteris band and adjusts throttle output accordingly.
Where you will see "look-ahead" technology at work in the automotive field, it's rallye-driving. There, the navigator will give the driver instructions on throttle, brakes, and gear choices for each section of road, based on advance reconnoitering. Thus, the navigator is optimizing the speed of the vehicle by letting the driver come as close as possible to the edge of wheelgrip without going out of control.0 -
Outdoor Reset
There is no reason newly installed Hydronic systems should not use outdoor reset you are talking a couple of hundred bucks, if for no other reason than added comfort.IMHO.
Now it only stands to reason that if you can lower your supply and return temperatures you lower your distribution heat losses, wich should give you a more efficient system.
And if you keep the system temperatures from over shooting you would also reduce your heat loss at a given temperature.
Or am I missing somthing please feel free to corect me if im wrong.
S Davis
Apex Radiant Heating
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Constantine...!
This is what i have been telling teckmar for YEARS,get the pump cold option going on! Today Zei wei and George stopped by to help me ...one of the things we disscussed was an idea i have to build a chip for a taco control that would allow that feature..George knows how ta lash up all manner of fancy computer stuff and Zei Wei can designe model and build all manner of robotics chips etc. me i just crazy enough to put some few dollars into the idea:)0 -
Hey I think Radiant Cooling is HOT!
...the question is how to best implement it. So far, the Karo system shows the greatest promise, yet how many people have real experience with it in residential applications?
Think of how much more space could be saved in homes even vs. high velocity systems, when the only heat that has to be removed the old fashioned way (i.e. using fans) is the latent heat.
However, the control strategy would also have to be much more sophisticated, i.e. detect when windows are open, etc. While such added expense makes more sense in parts of the world where energy conservation is a bigger priority, I suspect you could get a bigger bang for your economic buck back here in the US simply by switching to a DX ground-loop system.0 -
5X
> You're right on, Ron,
>
> There is a big
> difference between steam and hot water as far as
> boiler content goes. In the steam boiler, the
> water stays there until it evaporates and it is
> renewed only very slowly, while in a hot water
> boiler, the circulator is constantly whisking
> those gallons away. After a minute, how much of
> the original water will still be there? Probably
> none.
>
> A 100,000 BTU/H boiler on hot water with
> a 20 degrees temperature rise demands 10 gallons
> per minute, that's 600 gallons per hour, the same
> boiler on steam needs to boil away only 12
> gallons per hour, that's fifty times less.
>
> So,
> for a water system, the warm up time has to
> include the total water in the whole system, for
> steam, well, there is no other water than the one
> in the boiler.
>
> The time to heat one boiler
> load of water only is more or less identical in
> both cases, it only takes a few minutes.
>
> Once
> the water is boiling, it's a round of steam for
> every radiator in the house. This goes real
> quick, steam is designed to travel at speeds like
> 25 miles per hour! How big exactly is your
> house?
>
> Hot water travels quick too, but the
> warm up time is slower because you have to bring
> the system contents up to heat, the total content
> is many times the boiler content. If we assume it
> is five times the boiler content, then it follows
> that a hot water system will warm up in fives
> times the time it takes for steam, maybe a little
> less allowing for the lower water
> temperature.
>
> For the 18 PSI question, here is
> what I think. First off, why on earth would you
> need 18 PSI, if it is only to overcome the
> friction loss of a standard house, which is on
> the order of 1/2 a PSI? Your home would be hot
> as soon as the boiler had built up the first 1/2
> PSI, then, with that achievement under the belt
> it could leisurely build the remainder of the
> pressure but the house would already be
> hot.
>
> How long would it take? well, I am
> reading from a steam table, it takes 1151 BTU per
> pound of water to build steam at 0 PSI, that is
> at atmospheric pressure. To make the same amount
> of steam at 18 PSI we need 1166 BTU per pound.
> The difference between 1151 and 1166 represents
> an increase of 1.3 %. It does not take a lot of
> energy to build up pressure with steam (but if
> you don't need it, it is still a waste). The time
> it would take depends on how big your system
> volume is, it's like inflating a tire, it takes a
> certain amount of time. At 18 PSI you have a
> squeezed in a bit than double the atmospheric
> pressure, so it's like filling your system twice
> and the second time is slower than the first. If
> you closed the boiler steam valve, your pressure
> would rise frighteningly fast.
>
> Hey, it is nice
> talking to you, and gosh, I am long
> winded.
>
> Thanks for reading,
>
> Christian Egli
> You're right on, Ron,
>
> There is a big
> difference between steam and hot water as far as
> boiler content goes. In the steam boiler, the
> water stays there until it evaporates and it is
> renewed only very slowly, while in a hot water
> boiler, the circulator is constantly whisking
> those gallons away. After a minute, how much of
> the original water will still be there? Probably
> none.
>
> A 100,000 BTU/H boiler on hot water with
> a 20 degrees temperature rise demands 10 gallons
> per minute, that's 600 gallons per hour, the same
> boiler on steam needs to boil away only 12
> gallons per hour, that's fifty times less.
>
> So,
> for a water system, the warm up time has to
> include the total water in the whole system, for
> steam, well, there is no other water than the one
> in the boiler.
>
> The time to heat one boiler
> load of water only is more or less identical in
> both cases, it only takes a few minutes.
>
> Once
> the water is boiling, it's a round of steam for
> every radiator in the house. This goes real
> quick, steam is designed to travel at speeds like
> 25 miles per hour! How big exactly is your
> house?
>
> Hot water travels quick too, but the
> warm up time is slower because you have to bring
> the system contents up to heat, the total content
> is many times the boiler content. If we assume it
> is five times the boiler content, then it follows
> that a hot water system will warm up in fives
> times the time it takes for steam, maybe a little
> less allowing for the lower water
> temperature.
>
> For the 18 PSI question, here is
> what I think. First off, why on earth would you
> need 18 PSI, if it is only to overcome the
> friction loss of a standard house, which is on
> the order of 1/2 a PSI? Your home would be hot
> as soon as the boiler had built up the first 1/2
> PSI, then, with that achievement under the belt
> it could leisurely build the remainder of the
> pressure but the house would already be
> hot.
>
> How long would it take? well, I am
> reading from a steam table, it takes 1151 BTU per
> pound of water to build steam at 0 PSI, that is
> at atmospheric pressure. To make the same amount
> of steam at 18 PSI we need 1166 BTU per pound.
> The difference between 1151 and 1166 represents
> an increase of 1.3 %. It does not take a lot of
> energy to build up pressure with steam (but if
> you don't need it, it is still a waste). The time
> it would take depends on how big your system
> volume is, it's like inflating a tire, it takes a
> certain amount of time. At 18 PSI you have a
> squeezed in a bit than double the atmospheric
> pressure, so it's like filling your system twice
> and the second time is slower than the first. If
> you closed the boiler steam valve, your pressure
> would rise frighteningly fast.
>
> Hey, it is nice
> talking to you, and gosh, I am long
> winded.
>
> Thanks for reading,
>
> Christian Egli
0 -
5X
"Hot water travels quick too, but the warm up time is slower because you have to bring the system contents up to heat, the total content is many times the boiler content. If we assume it is five times the boiler content, then it follows that a hot water system will warm up in fives times the time it takes for steam, maybe a little less allowing for the lower water temperature."
To take water at 65° to say 120 will take 55 BTU's / #
To take water at 65° to 213 will take 1026 BTU's / #, or 18 times the energy required to heat th water for a radiant system. Remeber that there is the layent energy content to consider.
So if you have 12 gallons in a steam system, you will use 12312 BTU's to generate the steam, with 60 in a water system, (5x a steam system) you will use 3300. ( I am using round numbers for ease) But still its only a 1/4 of the energy. Add in outdoor reset, and radiant to me wins hands down on fuel usage.
Steam heat however IS very comfortable, and done right, quiet.
0 -
exactly, you gotta believe
> do you believe that cruise control
> save gas when used in your vehicle? If so,
> outdoor reset is a similar, understandable,
> concept when explained to the homeowner this
That's what I've been saying...you must ask not for proof, you must go with how you feel.0 -
After calling me a flame baiter you have just confirmed everything I said. There is no proof. It is a matter of seeling it to the customer based on their feelings.0 -
It is anecdotal for me. I had a client do nothing else but install outdoor reset on an existing six zone baseboard system, and watch his fuel usage drop about 20%. Are there factors that influence that number? Undoubtably. Do I tell clients they will save 20% energy? No. Do I tell them it increases efficiency? Yes, because it does.
Scientifically admissable or not, that's proof in my book, and the features of feedback systems beyond fuel efficiency justify them many times over when dealing with radiant systems.
I don't invent or design boilers or their burners. I do, however, observe how well they work with outdoor reset/indoor feedback systems attach, and I'm not going to ignore a known benefit simply because I don't have the necessary physics under my belt to explain *exactly* how it (or cruise control) saves energy. It does.
_______________________________
Northeast Radiant Technology, LLC
Robert Brown, Co-Owner, RPA certified Radiant Designer
207.899.2328
NRT@maine.rr.com0 -
Allow me to disagree
Note the points I made above. Anytime a heating system consistently matches the output of the heating plant to actual heating requirements, you will maximize comfort and energy efficiency. That is, unless you like to live in a house where the indoor temperature varies significantly.
Apparently, 94% of Americans do, because they use air-based heating. However, even on the scorched air side, folks have started to use variable-speed blowers to help lower the variability of air temperature and multi-stage gas systems to help modulate the temperature input. Since air-based systems have so much less mass than water-based system though, the impact of outdoor reset is not as great over there. Besides, they usually can switch to cooling if they have to.
In closing, it has nothing to do with belief and everything to do with understanding the physics and dynamics of heating systems. The biggest trouble is explaining these features to most consumers who have not taken control theory classes and therefore cannot easily grasp the significance of anticipating future heating needs easily. However, heating folks might be well advised to make analogies for different backgrounds to help illustrate the concept of outdoor reset. Here are a few:- Manufacturing: Using ERP systems to minimize inventory, yet have enough on hand when you need it (just in time inventorying and all that). Kanban systems work great as long as the demand is steady and/or your supplier can react quickly to fluctuations. Otherwise, you're hosed and hence need to keep a lot of inventory on hand.
- Police/Fire/EMT/Airlines/Hotels/Travel: Certain times of year naturally require more staff on hand to keep a lid on things. Your staffing levels typically have to be arranged in advance, hence you set them up to maximize presence when you anticipate the biggest need. Here, historical precedent allows you to anticipate future needs.
So, once again, it has nothing to do with beliefs and everything to do with finding analogies to events in "real life" outside the heating world that people can relate to. As I stated above, IMHO a cruise control analogy is flawed because it does not look ahead.0 -
JQP: May I suggest a control theory class..
...there is plenty of scientific proof why a properly controlled system will be more efficient than one that isn't.
Once you understand the beauty of a PID controller in this sort of application, the anecdotal evidence that the installers here have collected will make a lot more sense. Note, even though the knowledge of differential equations are allegedly a pre-requisite for this type of course (laplace transformations and all that), I found that a good control-theory professor will teach you all you need to know re: the math in very short order (2 hours or less).
Then sit down with Simulink and see how well different control strategies work at maintaining an even temperature, voltage, whatever. The beauty of control theory is that it applies to all fields of science, whether heat, electrical, physical, etc. Cheers!0 -
You missed something, Mike
That pound of water fills up a pint of your system, as water.
As steam, it fills 1700 times that.
Let's go by volume. The radiators fill that way, not by pounds. How much system will that pint of water heat?
Noel0 -
I agree
I was just showing his 5X thing being wrong...but thank you for pointing out the error in my limited example.
Clarification educates us all.
Mike0 -
once again for the FB
> After calling me a flame baiter you have just
> confirmed everything I said. There is no proof.
> It is a matter of seeling it to the customer
> based on their feelings.
Handy how you ignored the first paragraph of my post. I note that you haven't contributed a single piece of information to the discussion, just thrown mud. Also, you don't put your name on anything. I've been on forums and mailing lists for 20+ years, and these are all classic tactics of a flame baiter.
perhaps I was too subtle. Like I said, SHOULD YOU CHOOSE TO IGNORE all existing and current research in the field, including internationally, and disregard any physics and computer models, then you could say it was all snake oil. They have scientific evidence from many disciplines that demonstrate the gains from various forms of adjusting source heat to the emiters helps efficiency. Different setups, different savings but a consistent message.
This is a forum for trades people, with only a smattering of researchers and engineers. So it's easy to throw the "not scientific" arguement at these people. Why don't you tell the folks at the US national labs and any number of European universities that they aren't scientific about this work. Then, no doubt, you would say it's not real world.
What I was trying to say was that you won't get scientific information from homeowners who upgrade. Lots of reasons I stated before, but that's the bottom line.
ta ta,
jerry
0 -
three to one rule on return H2O temp.
As long I has have been in the business, Viessmann, Buderus et all have long preached for every three degrees you lower you return water temperature, you save 1 % on fuel bill. I always use this formula with homeowners to try to convince them of the payback schedule of radiant and other low temperature hydronics strategies (outdoor reset being one of them). It seems to work OK for me.
Wild Bill0
This discussion has been closed.
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