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Infloor Radiant Heat issue
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Comments
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I'm back!!!
Hello, Still working on a solution to lower my heating costs. Just had a heat loss analysis done by electric coop from info I supplied. They came up with a heat loss of 33000 BTU. My boiler is 34000 BTU. So it seems possible that the boiler would need to run at its full potential to keep up. I was contemplating trying to find a gas heater to supplement to get the dual fuel rate. But I'm wondering if I shouldn't look into a gas boiler to work in conjunction with the existing electric?? This would allow for dual fuel rate as well as provide sufficient heat to the system?? Also could allow for future expansion for other radiant options? I realize this would be more costly but possibly a better option. Thanks! Ray0 -
Resolution
I would go with a small mod/con period. You could use the thermolac for unoccupied periods to just keep the setback temp. Can't remember if you have ng or lp available.0 -
Resolution Idea
Hello. I appologize for my ignorance but what is does is a mod/con?0 -
Resolution Idea
Also, we only have availability to propane....no NG at this time as we are 11 miles out in the woods.
Thanks!0 -
Boiler type
A mod/con is a modulating condensing boiler very efficient in the upper 90's. They are lp, or ng. They modulate their output to the demand.
Only draw back is lp is not as stable as ng in pricing, but maybe some of the discount for dual may help.
Gordy0 -
Clarification
Thank you for the clarification. What size do they typically come in BTU's? Would I look at something similar in size to the existing electric boiler? Do you have a ballpark as to the cost of such? I'm guessing I wouldn't use that much gas as typically we'd rely on the electric unit. We would cut our electric rate from $.0943 per KWH down to .0552 per KWH on a dual fuel rate. I believe I've pretty much the set up for the control of the heat. Electric coop just needs to install the 2nd meter which the housing is already there. They will return the control unit for the controlling of the electric boiler. Does the propane unit need to be mounted on an exterior wall? That may be my only issue as the utility closet has access to an outside wall. However, the wall is under the landing of the stairway and the water tank/pump are in front of it.
Thanks!0 -
Free standing
Try looking at installing free standing large cast iron radiators to warm the space up quicker till the radiant catches up. Cast iron also holds its temp for long, so the boiler may not run often for it to keep.comfortable.:NYplumber:0 -
Depends on your plans
Is this going to be your retirement home? Are you planning on staying year round?
I think the best idea might be an LP boiler. You could look into heat pump mini-splits, then you'll have air too. They will heat down to -5*. It will get colder than that up there tho.
Heres a few pics, these are located near Bemidji (not year round, but close).0 -
Feedback
Thanks for the feedback on the radiators and mini-split system. I've actually seriously looked into the mini-split. But the majority of people I have spoken with that have them do so mainly for the A/C factor. If it was a seasonal usage place, that would be OK as well for some efficient heating. However, I don't think it will help us in the cold months of December - February.
Our main objective is to cut heating costs (electric) to a dual fuel rate. I believe that is my best alternative to be able to go from $.0943 per KWH down to $.0552 per KWH on our electric boiler heat.
After having a heat loss analysis done, I'm thinking that maybe we need more than just a gas supplement heater to get the reduced rate. Maybe it makes sense to go with the gas boiler to help keep the system running as efficient as possible. As mentioned earlier, I have a 34,000 BTU electric boiler with a 3 loop hydronic system in the concrete slab. We don't have an issue with keeping the place up to temp while we are there. But for the amount of time we are there and using it, it seems to cost too much to heat. Therefore, the reason to get on a dual rate. The heat loss analysis done, which is as accurate as the info I gave the electric cooperative that completed it (see attached).
Does it make sense that a propane boiler would help supplement the electric boiler? Or are we going to have overkill with the 2nd boiler and spend more $$ than it is worth? I know the heating loops will only but out so much heat (or as much as the body can tolerate). I would guess we could possibly add on radiant heat panels down the road if we want with the 2nd boiler system??
Again, still looking for the best alternative to come up with the most efficient and cost effective avenue. My original thought was to go with a vent-free gas heater (inexpensive to install) but possible issues with moisture and health hazards from different discussions I've had. Installing a direct-vent heater would bring the cost up quite a bit. So due to the fact of limited space available for a heater and cost of such, it has made me think about the propane boiler.
We do not get any rate decrease for off peak with a mini-split system and we would need to have a ducted heat system to use a standard heat pump for that break according to our electric coop.
Thanks for the suggestions!
Ray0 -
High heat loss
46 btus a square foot is pretty high. Your only going to get 35 btus a square foot out of the floor radiant, so you need supplemental. Your walking the line with the boiler you have being only 34000 btus.
You pretty much only have a few options.
Get a mod/con properly sized, and ditch the electric boiler on eBay., and add some rads.
Use both boilers with the electric for setback while gone, and the lp for occupancy. Pray lp market is stable.
Keep things like they are Bite the bullet with the present boiler, and add some supplemental rads see if that helps in the heating. Add the lp boiler later if extra emitters don't drop the electric bill. Either way you could use more emitter to help heat, add the gas boiler as a last ditch effort to drop your rates. This way you could do it in stages. Least expensive first with the emitters panel radiators can be elegant, and space saving.0 -
Best Thread Ever! :-)
Ray, Gordy, et al:
What a wonderful, nearly year long, thread! I miss Mark's post however! :-(
Our company in Washington State is a residential builder. We build spec homes using Insulated Concrete Forms...and the homes include radiant floor heat in a slab on grade. Not average for our area. But since I'm the boss and I think crawl spaces are evil, that is what we do. :-)
One thing I always mention to perspective buyers and those who are interested in what we're doing is that radiant floor heat (IMHO) is rarely going to be the least expensive heating option. With that said however I believe it is the most comfortable type of heat for human occupants...and possibly the best in regards to IAQ (indoor air quality).
In reading the thread tonight (and thoroughly enjoying it) and looking at the pics Ray has posted, I would suggest that his vacation cottage looks very nice, i.e. high end, for which he is fortunate indeed. Growing up in Eastern Washington, when we said we were "going up to the cabin"...it REALLY was a cabin! What I mean by mentioning this is, typically in a high end residence (irrespective of size in sq. ft.) comfort and occupant experience is of more importance than low cost of ownership. I don't know if Ray has talked to the original owner regarding this but I would bet that lowest cost of ownership was not the first goal when designing and building the cottage. Just my supposition. With that in mind however, once the utility's control device that should NOT have been in use was disabled, and he installed what seems to be a way better functioning tstat, I think the system is working well, i.e. as designed. Not inexpensive, but well and as designed.
From my admittedly limited knowledge of radiant floor systems (and further limited by all we do is radiant floor in slab on grade) I put forth that in the cold parts of our great nation, one layer of 2.5 inch EPS or XPS foam board under the slab is fine to make it work well, but not nearly enough to make it the type of cost effective heating solution that Ray and countless other owner are looking for. We need to start following our "net zero" pioneer brothers and sisters by ALWAYS putting multiple layers under the slab. R-30 should be a minimum with R-45 and R-60 the norm in places like his locale in northern MN. The cost increase on a modest sized residence would be approx $500 to $2k during construction, but would make the home more comfortable to live in and make the radiant system perform, cost-wise, MUCH more in line with the typical desires of the owner over the life of the structure. This of course assumes that proper foundation insulation, and better yet "frost-free" horizontal insulation out from the foundation options as detailed previously in this thread are also incorporated.
With that said, I STRONGLY urge Ray NOT to install a ventless gas heating appliance of any sort...if he likes the people who will be in the building during it's use that is! :-) Installing a second boiler running on LPG would indeed cut his power cost per KWH nearly in half...and give his system more goose re: bringing the slab back from setback. With that said however remember that the "P" in LPG stands for "petroleum"...or in other words "oil". If the goal going forward (over hopefully many years) is controlling heating costs, adding a component that runs on fuel made from oil might not turn out so well. :-)
My personal solution would probably be:
Add the LPG boiler. Granted I say this since I can do the work and the only cost would be materials. This would drop the KWH cost nearly in half and provide the other benefits mentioned above. In addition it would provide something I personally ALWAYS include in designs but have not heard here: provide for backup in case THERE IS NO POWER! Granted, fully implemented, this option would include a battery powered tstat and a UPS for the pump...but those two things are relatively inexpensive. I actually always spec a gas fireplace so if the power is out (and in this case the UPS for the pump runs out before the power comes back on) we still have heat. Granted this doesn't cover you if the power is out for a LONG time when you are not there and the power of the UPS runs out. It does cover you however if you are there and can fire up the portable generator in the shed. Also, since of course the outside BBQ is also fed off the LPG tank, there is full blown cooking even when there is no power. And by the way, it tastes WAY better when everything else is going sideways due to no power but there is still a hot meal!!
I realize that a real fire is often more desirable than a gas fire, but not having to get out bed when the power is out to put more fuel on the fire in the middle of the night makes big points with the wife. Also we are trying to be covered when the power goes out in the middle of the winter and we are not there. PEX tubing in the slab (and elsewhere in the residence for that matter) is indeed forgiving re: freeze/thaw compared to other plumbing options...but I would prefer to not press my luck.
Many, many thanks to Ray for posting his initial query and to all you great folks for making it one of the best threads I've read anywhere, on any topic! MUCH apologies for the very long winded post!!
Thanks
Jeffrey Bruton0 -
Still Covered!
It's so late that I forgot....our newest home (like our last one too) is fine even if the power is out for a very long time. There is a separate t-stat for the fireplace which runs off batteries...and the wonderful little Lopi Northfield LPG gas stove has either normal free standing pilot (on all the time) or electronic start pilot which is battery powered...so you are covered for as long...well...as big as your gas tank and the batteries I guess. :-)0 -
Forgot that...
Lying in bed last night I remembered a UPS for the pump, battery t-stat, and full propane tank are not enough. You still would need a back up power source for the electronics in the boiler or the zone control panel, whichever your t-stat connects to.
I remembered this is why I always provide back-up heating via the LPG fireplace/stove and battery t-stat...which provides automatic, unattended, back up heat for a very long time.
Maybe no more posts late at night, eh? :-)0 -
Electric heater
What are the thoughts of using a suspended electric heater to help supplement the existing system. It would assist in helping the radiant system keep up and also help with quick heat up of the place??? We have one in the room above our garage up there which we use occasionally. It warms up fast and has to be on low to keep from getting too warm. Are these available with a separate thermostat from the unit to control more precisely? I was thinking that it would be a fairly inexpensive addition and may help conserve electric usage from the boiler standpoint??
Thanks,
Ray0 -
suspended electric heater
Something akin to a radiant trough? That would quickly make the space comfortable. Wire it to a suitable TRIAC thermostat (think Aube/Honeywell) set a couple of degrees below the main stat and you should be good to go.
What size is your electric service?0 -
Suspended Electric Heater
These are the electric or gas units that are attached to the ceiling, typically in a garage or shop. My wife doesn't think the one in our 14 x 26 room about the garage is too bad looking.....light tan color. They heat up quickly. It's not going to give me a break in the electric rate but would possibly help the infloor system from working hard to keep up?? Going with the propane unit would give me about a 40% discount in rate for electric heat. The unknown is the cost of propane to heat when electric is controlled or to help supplement the electric system. Also the cost of the direct vent heater, etc. is going to be a considerable amount to install. These electric units are relatively inexpensive to purchase. Just don't know how much it will help lower cost of KWH??
Thanks!
Ray0 -
questions and things to consider
Have you tried to turn temps down further when you are not there. Rather than just 55f.
You are heating the house weather you are there or not. It appears your electric bill is not to much affected by your visits as they are fairly short. That means you have several solutions to bring costs down. They fall under 2 categories.
1 get cheaper electricity. Definitely a viable option but no guarantee where rates will be later. Seems to be the low hanging fruit.
2. Use less electricity.
a. Do not heat house as much when you are not there. It appear from the document attached that January had temps averaging about 0F .
If you could change set back from 55F to say 50F you could save a good bit.
I will use 55F as standard and compare what heat loss should be as a percentage.
70F = (70F-55F) /55 = roughly 27% increase in heat loss.
60F= (60-55)/55= roughly 9 increase in heat loss vs 55 degree
50F= 50-55/55= roughly 9 percent drop in heat loss.
45F= 45-55/55= Roughly 16 percent drop in heat loss.
40F= 40-55/55= roughly 27 drop in heat loss.
35F=35-55/55= roughly 36 percent drop in heat loss
you get the idea. I think some saving could be had but just setting thermostat down a bit further when you are not there. It seems you are far away and visits are not spontaneous so you could have the heat turned on maybe 4 days in advance. Your heat loss drops when inside temps do as well so house should be fine. Heat loss Calcs were probably done assuming inside temp of 70F. Well heat loss at 45F are roughly 36% of what they are when at 70. So heat loss number of 34000 becomes 21k-22k
b. More Efficiently heat the space. This can be done many ways. But your current system is getting less than 1 cop.
http://www.businessdictionary.com/definition/coefficient-of-performance-COP.html
Your electric boiler will run at 1 cop but the entire systems with pump and everything will bring that down to under 1 cop.
You were talking about a mini split. Seems like a good idea to me although it should only be used to supplement due to your weather. I would make sure it was one that did not have an electric heating element in the outdoor unit. Some units to make sure they perform when outside weather gets cold have an electric heater in the outside unit. Kills efficiency. Anyway efficiency will be much lower when it is around 0F. But at times when the outside is in the teen and up, your COP should be above 2 and in shoulder months it should be probably higher than 3 cop but depend HIGHLY on unit. Not all units will work in the cold. Maybe a centrally located single 18000 btu unit would help the floor a lot. IN shoulder months this should drop electric usage a lot. Maybe in half. Weather of not that will payback fast enough is another issue.
b. Heat more efficiently by reducing the need to heat. Better seal the house. I know it is not glamorous at all, but simple air sealing by owner diy has incredibly fast payback. Basically any air that infiltrating the house bypass any insulation and diminishes it value.
It would be like filling a bowl with water that had a few small holes in its bottom. As long as the facet is on the bowl would be filling with water. But as soon as the facet is shut off, the bowl empties in short order. Even if the bowl had walls 1 foot thick the wholes with bypass and escape quickly.
I would take an infra red heat sensing gun and check all around the house. Big culprits are windows and doors, and recessed lighting and outlet boxes on the walls.
Basically go around with the gun and check near a recess light, then on the light unit. Obviously light is turned off to not heat the area. You could be surprised. A few feet away maybe 60F and you get to the light and it is 35F or lower. You do this for anything coming into the room from the walls. Windows will read lower, but it should be fairly even all around a window, if not there is an air leak.
Now document your problems if there are any, which there probably is. Now go about solving the issues. Afterwards you will lose less heat. This will save you money all the time, what ever fuel source, it does not wear out, it is there for the life of the house. It is not flashy but has a great return on investment. Probably not what you want to do while visiting the house, but it really is not a mansion so not so long. Maybe identify problems one trip and next trip solve them.
Anything that can reduce heat loss will make current and future work less. I read somewhere although I do not know the validity of the statement but was. The AVERAGE US house has an air infiltration equivalent of have a door wide open. Probably not your case as the structure is small. But most people dismiss small leaks of air, but would close and outside door pretty quickly. Small air leaks add up quickly.
To address your last post.
I myself would not throw and electric heater in the house that had a cop over 1 or less.
Also something to think about with propane, and I think another post already mentioned it. It can be of great assistance if power goes not there. Not sure your intentions at the property. I mean if power goes out there, you could just end trip and go home etc. But a propane heater works with little electricity. What would happen at your house if electricity went out for a week? Water lines in the walls? Water in the toilets, etc.
This brings me to my last comment and this one would save you money quickly although some things to think about before implementing. How about short term winterization. Have fluid in heating system be antifreeze. If it is easy to drain all water line in the house. Depending on how house was built it maybe very easy.
Basically shut house down when you are not there, and 5 days before a visit have neighbor turn heating up. For the first 2 days the house heat loss would be very small, and things would heat up very quickly. Once the house starting heating up recovery rate would slow down. There are many things to investigate with this method before implementing.
Just some thoughts. It seems turning thermostat to 45F would be a quick solution to start lower usage.
Sorry for any typos. It is Christmas and have to get going.
matthew0 -
Mathew
Have you absorbed the whole thread? Part of the initial problems were inability to maintain set point, and high operating costs.
With those two issues in mind, and RFH as the emitter with an electric boiler that is right to the limit in sizing to the heat loss of the dwelling no emitters on second floor.
The more you setback the longer it takes to get the dwelling to set point for the times of occupancy. Yes you will save more in unoccupied periods, but it will take more time to get the dwelling to temp for occupancy. If there is a power outage the lower the set point the less time you may have to deal with an unwinterized cabin.
Even when heating with propane the boiler is electricity dependent.
Personally I think window treatments on all glass would dramatically improve heat loss alone. Lots facing north.
A pellet stove may be an alternative supplemental heat source during occupancy also providing convection heat to the upstairs. The existing fireplace is prefab with stone veneer over framed chase. That stone veneer is a lot of mass that sucks from the MRT in the room for quite some time. You can buy pellet stove inserts that resemble a fireplace which may swap out with existing prefab. You would have to vent it through the wall in the back of the chase you already have a fresh air intake for the existing prefab fireplace.
The way this thread is going the OP wants the lowest cost solution possible, and the lowest electric bill possible.0 -
Yes I read it all
At lower temps heat loss is lower. Raising it from 45f to 55f with current boiler would not be an issue as heat loss will be much lower. The problem comes from raising it the last bit as heat losses are getting higher and closer to the limit of the system. So if the house is already at 55f and has little issue getting to a reasonable temp going to 45F just means starting heating earlier. With the amount of empty time house has it would save money overall.
While am an not a pro, it is simple math, and investigating abnormal heat losses.
I find most people do not want to have good quality window treatments, although alot of heat savings can be done there. I say good, goes beyond a simple window shade that does not seal the air cavity between it and the window. Say the walls are supposed R-19 forgetting thermal bridging etc. Windows are an R2 maybe R3. With good window coverings you could bring that way up. Cutting losses from windows down dramatically, baring air infiltration problems. So I do agree. It would be a good way to reduce heat demands.
But deep set back is not a big issue. Thermal mass can only store so much heat or lack of(cold). So even if the house was at 0F it would take a certain period to heat up. From 0 to 30F would happen much quicker than 30f to 60F. Boiler efficiency would be the same but not the houses. Heat loss calcs are house at temp, not at 45F. So heat loss is way down when temp goes down. Simple math.
It would require a longer time to heat up, but the overall saving would be there. I can guarantee it especially since we are talking electric boiler with a fixed efficiency.
You are correct about the power going out and starting with lower temps and quicker freezing. Fairly easy to make a backup system for a propane boiler. A small 1000 watt generator would be more than enough, or a few deep cell batteries, alpha circ pump would help as well.
I am sure that fireplace stone is taking alot of time to heat up. Old house I lived in had something similar in size. A bit wider but a bit shorter, but was built will full stone, not veneer. I used to have that space set at 50F when not in use. Using baseboard radiators. When I turned on thermostat it would take maybe 12 hours to get up to temp. There are alot of variable, but it does have alot of thermal mass, much more so than any other single component of the house baring the slab.
Another issue that deals with comfort and not cost would be to turn up temps in the day time to charge the slab more. You could have temps in house maybe go to 74F, and night it would still drop down a bit, but you would start higher, although the drop in temp to say 67F would probably not feel so good after being at 74F. Also it would cost more to do it that way. Another variation could be have thermostat set to 70F during day and at 3pm turn it up to 74f. It should start ramping up slab temps but really not effect space temps much.
And yes I read the whole thread. Getting cost lower by getting electric rate less seems more accounting type of solution and while it works I am more into lower heat losses as well, as it is less dependent on a electric rate that could change at any time.
Unless builder paid extra special attention to air sealing the house there is alot of air infiltration that can be tackled. I personally believe the radiant slab hides the drafty nature of certain houses. So heat loss is similar with a baseboard system, but different air flows.
One question what does outdoor reset accomplish on a slab. I see there being little value to modulate water temps in the slab if boiler efficiency is always the same. Seems better to use higher temp fluids and pulse/(turn on and off for certain periods of time) the circulator to safe pumping power.
Will the outdoor reset start the heating system if house is to temp, but outside is dropping in temps? Did not understand if the outdoor reset is now working or not. Seems like only useful if slab sensor was used in the controls so even if room is to temp the slab sensor would start heating before slab temps start to fall drastically. I suspect and just really a guess that house is getting to temp in early afternoon. and system shuts off. The mass in the floor is keeping room temps up for a while, but then slab temps start to drop fast and the marginal heating system has to fight a slab that is already dropping in temps. Really easy to test. Say at 2pm turn heat to 75F and see what happens during the night. This is eliminate any slab cooling period. While it will use more electricity, it will tell if added controls would help with the comfort aspect.0 -
heat loss for OP
I think I can present heat loss numbers a bit better.
Now based on 70F as baseline. And averaging ambient outside 0F over entire month.
55F setback has heat loss 55/70 =78.5% as 70F. So whether you are there or not your are heat that house alot.
45F setback 45/70 = 64% as 70F.
You being at the house 4 days a month(70F) is the equivalent of 5 days unoccupied at 55F.
I think OP does not realize how much he is heating if he is there or not.
Another way to look at it is if bill is $180 for the month unoccupied. Occupied would be around $230. To me does not sound tremendous considering he is using an electric boiler. So op is saving $50 doing the setback roughly. Maybe more with air infiltration and other misc.
Ambient temps are brutal there.
Try to lower demand, and getting a lower electric rate would help.0 -
outdoor reset and slab heat
were made for each other, which most of us understand quite well. Have you ever lived with a high mass floor running bang-bang on a conventional boiler? The over- and under-shoot can be maddeningly uncomfortable -- and it burns far too much energy. Properly commissioned outdoor reset produces superior comfort and efficiency.
Window coverings have been suggested and may already be in place.
We have suggested using the existing electric boiler to keep the space at a stable, low temperature all season. Augmenting with overhead radiant will get the space comfortable quickly while the slab heat catches up to the desired occupied temperature. Adding thermal storage to take advantage of baseload rates or conversion to LPG are options that need to be explored.0 -
Mathew
Most new boilers do not operate on generator power especially small generators (dirty power supply). As has been seen here on the wall from hurricane sandy casualties.
I believe the op has the info needed, and now is trying to intelligently figure out best cost effective options. AC is part of this that's where min splits play into the picture.
I applaud the op for taking the time to approach options in an intelligent manor, and not throw money at the problem.0 -
matthew
Depending on what small generator. There are some horrible ones, but also some very good ones, atleast how I understand it.
Cheap chinese knock off probably not very good choice. It could be a bit of money for a good one. (Not a home depot special) The idea of a small generator is not to be cheap and save money on purchase. It is to be very portable, and usually lower noise levels and also lower running costs if your base load is only 500watts. Running a 5000 watt generator may work for a whole house solution if you want to run lots of loads, but for running 8 hours at night a small generator with lower noise would be my preference.
I have lived in off grid house in warmer weather location. Adding a 10 gallon tank to a small generator could run for a long time, or even a lp generator. Since it is a vacation property have a gas line plumbed to outside with inside shutoff. In case of need just carry small generator to location and connect. But really that is a whole other can of worms, or should generator be permanently mounted and fire automatically etc. Generator really not part of this post but somewhat easily achievable.
As for outside reset in this situation. Not sure that is contributing anything without a floor sensor? I think outdoor reset works better when you have a heat source that is sized with a bit more margin of heating capacity. This way it can crank up and heat the slab somewhat faster, or adjust for large swings in temp. But with a marginal sized heat source just not seeing the great benefit. It seems over shooting in the early evening would be beneficial here.
A sensor to monitor slab temps and make heating decisions seems better fit in this case.
Rather than modulate water temp.
I have never actually worked with the outdoor reset though. Fortunate to do staple up installs on several low mass wood floors. Much faster response time. And even a sandwich type similar to warm board.
As for window coverings I not sure if OP considers the shades he has to be them. While better than none, far short of what is available. Also the odd shaped windows by sides of fire place is a little harder.
http://www.builditsolar.com/Projects/Conservation/MylarStorms.htm
http://www.builditsolar.com/Projects/Conservation/bubblewrap.htm
http://www.builditsolar.com/Projects/Conservation/Astrofoil/AstrofoilShutters.htm
Mylar storms seem like they could be left all the time. Of atleast on the high windows. Low windows and doors could have the bubble wrap installed in a few minutes before you leave the house. Although some people do not like the effort involved, but it would cut heating losses a bit.
May want to check out builditsolar.com specifically the conservation section has alot of things that may help you.
Matthew0 -
Mathew
My charger for porter cable battery tools will not work even in high quality Honda, ranger type welder generators dirty power symbol flashes0 -
indoor and outdoor reset
The point of outdoor reset is to deliver the amount of heat needed to offset the envelope losses for any given outdoor temperature. Combining this with an indoor thermostat (acting as a high limit control) will produce better comfort and efficiency than most Americans have ever experienced. Really.
Slab sensors and indoor air temp sensors wired to a top-of-the line control can
make further improvements by dynamically adjusting the reset curve. I wouldn't even think of throwing out 95% of the benefits of outdoor reset just because I didn't get the latest 5% of possible refinements with it.0 -
comments and questions
I believe the boiler can supply 35000 btus . Without floor sensor.
Say it is 15F during day time, and -10F at night.
Say at 70F interior temp house is losing 28000 btus during the day. That would make night time heat loss roughly 41000 btus.
I know just guesses really, but I think something that is happening in this system maybe different numbers. Day time heat loss is lower than boiler can supply while cold nights brings heat loss higher than it can provide.
Would it not be better to precharge the slab during hours of extra capacity to prepare for when the heating system can keep up. From a comfort aspect seems like a winning situation. Will not save any money though. Still would be better to reduce heat loss so night time losses could be handled without buffering heat into slab.
It was suggested that thermal tank could be used to take advantage of base load rates. It could also be used to add heat to the system while boiler is being under utilized to be released at night when boiler can not keep up, But op said not much space. Not sure what not much space is? Thermal tank could be built really easy although I would venture to guess most here would buy a tank. If used electric tanks could be bought for cheap would be something to think about.
Not sure max temp boiler can supply.
2 -50 gallon tanks water raised to 130F(even higher better) say provide useful heat maybe down to 110F. Would only store an extra ~16k btus. If storage could be gotten higher to say 150F ~33k btu. That should cover extra heating needs, If water temps could not get so high adjust water volume would be useful, I personal am a fan of onsite built tanks, as they can be custom made to fit the space available. I would think for less than $300(material costs) a custom tank of 200 gallons could be built but depends on tank geometry. I built a 1200 gallon tank in a basement for no more than $2000 and that has 3 large heat exchanger(r50 insulation). Anyway this comment is getting away from me. I start typing and my mind starts wondering onto different possibilities although probably more non traditional from what most on here go after.
Trying to get back on track to really wanted to ask about is the out door reset.
I am really curious on how a out door reset would handle the situation in this case with boiler on the boarder of its limits(assuming there was floor sensor). I am not doubting out door resets in general. I am just thinking in this case with limited boiler it makes little sense to throttle the boiler back.
Does the outdoor reset learn it can not keep up with heating demands? How does that work. Is there a forecast based model that predict on future weather. It seems in this system if you did not predict ahead it is not strong enough to keep the system at desired temps.
Not doubting out door reset, just its usefulness in this case, especially mid winter weather. Shoulder months could be a different story.
Matthew0 -
In aunt shell
You are burning more electricity than needed either by charging storage tanks, or heating the slab more than it needs to be. This is all using more electricity which the op is trying to get away from.
Well designed radiant systems provide comfort. Adding a fly wheel effect to the slab by over heating during the day voids this.
The bottom line is the boiler size is so marginal to the heat loss that it struggles with deep setbacks the deeper the worse it gets. With that said for a weeks stay the house needs a few days head start to catch up,so to speak. For those few days its running flat out to get the mrt of the structure up to temp.
To lower the electric utility they need more emitter, and a slightly larger heat source of another fuel type....lp but that can be a crap shoot in today's markets. Plus the op wants to take advantage of the dual fuel special electric rate. Plus ac ability.
Ac options are window shakers, or mini split
Mini splits do not fair well for heating at low temps say 5*.
Pellet stove could help with heating dramatically especially if neighbor is willing to fire up the day before arrival. Plus the use little electricity, and will run on dirty power in an outage.
Ac honestly I would opt for a,couple of window shakers for their climate region.0 -
Back Again!
OK. After our largest electric bill ever....$333 for the month of January....we are forced to do something here! We used 2877 KWH for 31 days in which we were only there for 3 days at the end of the month. We are looking at a price increase in rates as well but don't know exactly what they will be at this point. Part of the $333 was a power adjustment of $31.
We are looking at a gas direct vent unit that will fit the minimal wall space we have available which is basically on the stairway landing about 5 ft up. We've researched many units but haven't found one that will work that is at least 80% efficient. Any ideas out there for vented heaters? We do have 2 ceiling fans - 1 in loft and 1 in main area of cabin. We can run those to help push the heat down.
Thanks!0 -
0
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KWH
That's 11.6 cents a KWH about the rate here in ill. Not the highest in the country by far, but expensive.
You really need to ditch that electric boiler, if your are going to see any real utility reduction. The gas heater is kind of a bandaid in my opinion. Money spent that could go towards the new boiler.0 -
LPG boiler
Put a PTS60 or a WHN055 in there and stop worrying. Much better investment, and with those electric bills it should pay back pretty quickly.0 -
Gas Boiler
I guess I can see the gas boiler as an option if we were going to add more radiant options other than the floor. But is a gas boiler of 40,000 or 50,000 going to put out anymore heat than our current system? I believe we are still going to get only as much heat out of the floor as there are corresponding loop lengths.
We had a contractor out to the place last Thursday while we were there. They wanted to slap a 80,000 BTU gas boiler in for $5000. However, they said they would turn the temp on the system up to get a little more heat out of the floor. But it still isn't going to heat sufficiently unless we bring more radiant units off that boiler at higher costs yet. It would be more cost effective at this point based on current prices of LP vs the general service cost per KWH. But it seems to me it would take a long time to pay for this upgrade in the amount of savings we would get.
With a dual fuel rate, we start saving instantly by a $.04 drop in electric rate. I'm by no means an expert but have done a lot of research. I just can't see the conversion to an LP boiler without adding more radiant panels around the place to help. I also believe we don't have the adequate space for a backup LP boiler to go that route either which is something I've considered.
Thanks guys for the ideas! I have learned a lot through this process.0 -
confused
Yes you are under radiated somewhat, but the goal here is to reduce your electrical consumption is it not?
Your bill reflects an average of 13200 btus an hour in a 24 hour period for the billing cycle. This is a very rough estimate if nothing else but the boiler is using electricity which we know there are other draws on power. So your boiler is using less than that, and more depending on the load at the time.
I think 80,000 btus is way to much. Like SWEI says go with TT 60 or a Knight 50. It gives you room to add some baseboard in the future.
You keep boasting these dual fuel rates. just throwing a wall furnace in to get the reward seems like a bandaid to me. If your going to do that may as well ditch the radiant all together. save the electricity.
Really dont know what to say I think you have researched this, and have been given plenty of opinions, and advice its time to make a choice. Nothing is concrete in utility rates no matter which way you go. Its to bad you do not have NG. But it could happen in the future.
By the way are you SURE no one is living there while you are away? thats a lot of KWH for only being there for 3 days in a month. My usage was 2029 KWH for a family of four at XMAS with lights blazing, and a dryer that is on about half the time.0 -
Appreciative
Gordy ...Don't get me wrong. I'm appreciative of all the feedback on help. I'm just getting frustrated with the whole situation. I've attached a copy of spreadsheet with the breakdown of billing since we've owned the place. I've added the columns highlighted in yellow as to what our costs and savings on electric would be over the time frame if we were: 1) Dual Fuel 2) Off-Peak (Actually we were off-peak the 1st winter there and no one realized it. We didn't have heat from 7 am to 11 pm each and everyday...if you recall from early posts.) I've also attached the day by day usage for the last billing period that was so high. I've highlighted the days we were there. We actually got there around 11:30 PM on 1/23. You'll note that some days are skipped but it is dependent on the time the meter is read so it could run over to the next day. We did run a 110 infrared heater during the time we were up there to help out. I gets chilly in the evening when the temp was below zero. We also used the fireplace in the evening when we were there during that time frame.
We also turn the heat down when we aren't there, turn off the water heater, and water pump. The only thing using electricity that I'm aware of is the refrigerator. TV, DVD player, and stereo are plugged in but off.
Thanks!
Ray0 -
Don't see the attachments
?
Got it.0 -
I see it
Seems you really do not use much more in terms of kwh while there maybe 6k at t the highest. Otherwise consistent during unoccupied times.
Just remember that you still want AC so that could be killer. Depending on how much occupied, and temps.
I think I would be cautious of predicted savings from the electric utilities. They just want to get you on board.0 -
Wish more people did this...
RCO, I'm reading through the thread. I commend you for doing what 99.999% of others don't; compiling the information into a mathematically communicative format.0 -
Thanks!
I appreciate the remarks concerning the data I've gathered.
We won't know for sure until April as to what the new rates will be for electric. The price on propane when I checked last week up there was $1.89. From what I understand, the current dual fuel rate of $.0552 is equal to about $1.33 per gallon of propane. I guess that is figured roughly at about 90% efficient for propane system used. At the current price of propane, an approximate break even would be $.07 KWH. I realize that propane is probably at a high right now or at that time due to the cold weather they are experiencing.
It may be worth waiting until spring to do further action because: 1) I'm already setup for the dual fuel or off-peak system. I've a separate service for the boiler system and wiring is out to meter post. The only issue is that the electrician would need to do a temporary jumper wire to a 2nd meter until it could be buried under ground and up through conduit. 2) Fuel tank/line would be temporary due to same issues. Each would need to come back out to bury lines in spring.
Are there boilers that are small enough to add a 2nd within the uitilty closet that houses the electric boiler? I guess I'd prefer going with a dual system rather than giving up the electric completely. That way I could still qualify for dual rate, use gas when more/if advantageous, and allow for supplemental radiant at a later time frame.
As far as A/C, we had one weekend this past summer where we really needed it. I've picked up one window unit and plan on another for room above our garage to use when needed. I'm not going to worry about A/C until we are able to use this place more on a consistent basis. The only reason A/C came up was during the exploration of the mini-split systems. That would have been the bonus of those. I still have a contractor who tells me that a mini-split system will definitely lower my electic bills and provide the heat I need.
At the point of time that we do retire and spend more time up there, we will then probably look at connecting the garage and cabin to allow for another bathroom, wash room, and utiltity area. Then we may look at other heating cooling options at that time. That is 10 years + in the future. Hopefully, we still have the place but only time will tell.
Thanks again for the feedback guys!0 -
arbitrage
If this were by my place, I'd really want to know why it required so much energy for me not to be there. The answer might well cause me to rethink ownership.
If I could get a 50+% reduction per kWH via some token LPG implementation I would probably take advantage of it. But not before understanding that first question.0 -
Thermostat
Hello. Just got to thinking about the thermostat. I had installed a new Honeywell digital thermostat back in late November of 2011 to replace the mechanical unit pictured within this thread. It has seemed to do a better job of holding temp accurately. It is a Honeywell RTH221B Basic programmable thermostat that I purchased at their local Wal-mart. I've attached details per PDF.
Would it be possible that I could've hooked this unit up incorrectly or set it up wrong in which it would keep the boiler running all the time? Just trying to think outside the box here! It seemed pretty basic and I don't recall the details when installing. Just want to rule that out as a possible issue.
Thanks!
Ray0
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