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WM Ulta and Viessmann Vitodens
Mark_34
Member Posts: 3
I have been looking to replace my 40yr old boiler. I like the looks of the
Ultra boiler but I don't know if I trust the cast aluminum heat exchanger. A good cast iron boiler you can get 40 to 50 years life out it but how long will cast aluminum last? A good cast iron boiler you can get 85% efficiency and the Ultra is like 93%. If the aluminum heat exchanger will only last at the most 20yr then the added 8% efficiency isn't worth it. I have also looked at the Viessmann Vitodens boilers and it looks like a great design. It is also made with stainless steel not cast aluminum. The problem with the Vitodens boiler is it only will supply water at 167 deg. F. Most of the old heating systems where setup to run on like 180/190 deg. water. You can only get so many Btu/ft out of your baseboard heater no matter how big your boiler is. Is there an easy rule of thumb to work out the temperature difference and feet of baseboard I will need to heat my house at the lower water temp.
Mark
Ultra boiler but I don't know if I trust the cast aluminum heat exchanger. A good cast iron boiler you can get 40 to 50 years life out it but how long will cast aluminum last? A good cast iron boiler you can get 85% efficiency and the Ultra is like 93%. If the aluminum heat exchanger will only last at the most 20yr then the added 8% efficiency isn't worth it. I have also looked at the Viessmann Vitodens boilers and it looks like a great design. It is also made with stainless steel not cast aluminum. The problem with the Vitodens boiler is it only will supply water at 167 deg. F. Most of the old heating systems where setup to run on like 180/190 deg. water. You can only get so many Btu/ft out of your baseboard heater no matter how big your boiler is. Is there an easy rule of thumb to work out the temperature difference and feet of baseboard I will need to heat my house at the lower water temp.
Mark
0
Comments
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168F and BBD
Mark,
Most older homes have so much "fudge factor" in the heat loss that you will probably find that you have enough to handle your heatloss. So, before you put in any boiler do a load on the house.
Then, as far as de-raiting your BBD. Standard BBD that puts out 600BTU/ft at 180avg will put out 500BTU/ft at 160avg. You can always increase flow and decrease delta T bringing up your average temp... but be careful not to exceed suggested flow in your copper or it could become noisy.
Make sure to have a great air eliminator (like a spirovent) in the system.
BTW - you can (with a little work) increase the temp on the Vitodens to 180 but by doing this you take the boiler OUT of condensing and thus greatly reduce efficiency (you do the same running the Ultra at 180F).
wheels0 -
.
.0 -
right
We reset the baseboard systems all the time always works great the colder the water the better for that type of boiler.We do it with the oil models on replacements and people love it they always say the house is much more comfortable. FYI The Viessmann is far superior the controlls are amazing you can watch the burner modulate as various zones open and close, simply amazing!
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Your basic premise is flawed
The least efficiency the W/M will get is 93%.
The best from a c.i. boiler is 85%
Realistically, the W/M will average closer to 96% making the savings over 10%.
If fuel costs continue as they have, the savings of 10% alone in 20 years would approach more like 4 - 5 thousand dollars - which just about makes the W/M free.
Then too, there is the nuance of math that says this: "The difference in efficiency between a 85 and 95% AFUE is not 10% The difference is 85 divided by 96 which is mathematically how we would get the true percentage differential - it results in 11.5% improvement.
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Question Joel
"...you can watch the burner modulate as various zones open and close..."
Have any of your installs used the low-loss header? If so, do you see this burner modulation?0 -
96% efficient at 160-180°
operating temperatures? Will Weil put that in writing
hot rod
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The only days we need 180
is on a design day.
Which is about 10 a year.
The rest of the year the boiler will be running closer to 98% than 93.
We don't need it in writing. We all know that's how it is.
Or do we?
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weil literature says.....
(how was that for Philly english!)
92% efficiency... Low Temp Seasonal efficiency of 96% based on a return temp of 90F and a supply temp of 110F.
Deceiving? Only if you read it quickly:-)
Mmmm, makes you thing at 170 when you are out of condensing mode that the efficiency starts to drop.
wheels0 -
Keep something else in mind,
Unless the boiler runs almost non-stop, it will always run at first start, with whatever the maximum potential efficiency it can achieve as the "standard" performance!
This is because the startup will have close to ambient return temps. So until the first slug of water actually makes the round-trip, ALL RETURN WATER WILL BE 60 to 70° water temperature! For the first minute or two, the boiler will be at the maximum possible operating efficiency because the return water as well as the outgoing will be below 100°!
Of course this only happens from a cold or ambient system start up. But we all know the that is far more frequent an occurence than a 180° all day long event!
On a 50° day, the boiler may only run from 80 to 100° and actually run well up and over the 93% range.
Of course load, zoning, outdoor reset, indirects etc also have an impact. But for much of the heating season, the boiler will start. And when it starts, many times it will be way below even the 110° you site as the 96% efficiency mark. The important thing to remember is that the boiler can not run without starting! And when it starts, it will attain way more than the stated efficiency. This starting efficiency must be transcended before real efficiency drops off to the low 90's. But it has to be transcended every single time the boiler starts - when system water temps are near ambient. With HWBB heat, that water will lose last cycles heat in around five or ten minutes (of course very dependent on how hot the water got on the previous cycle.
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My thinking
would be anytime it falls below condensing temperature at the return, say 130° F the efficiency would be in the mid or high 80's more like a conventional boiler. I'll bet a bb system designed for 180°F at design day sees a lot more than 10 days of above 130 return temperatures needed to keep it in 90% plus condensing mode.
Of course if you heat ONLY with low temperature radiant (below 130°F supply) that's where condensing boilers belong. I don't see a good $ value using a condensing boiler at 180° design temperatures. The greater benefits will be seen from the low mass and modulating feature, less bang bangs on the components, etc, in my opinion, in high temperature operations.
hot rod
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header
As far as I can recall all of our installs have had the low loss header. I just think for how we've been doing it, mostly replacements on exsisting systems it is the safest bet and really in the overall scheme it's small money. yes you can watch it modulate, well you can't see the fire of course but you can here the blower ramp up and down with the outer cover off. You can also see it happen on the controll.The setpoint temp and actual water temp will be say 1-2f apart and when a zone opens they spread apart maybe 4-10f? After that you'll here it start to ramp up and can watch the water temperature difference tighten up. It's very cool. With all zones on the boiler will be at full bore and as they close or the water temp ramps up you'll see/here it slow down, it's a good thing I don't have one in my house (have oil V)or I'd be down in the basement all the time watching it.
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HR
Your right that unless the return water temp is cold you won't condense, but you'll be close. The modulation feature is a huge performance benifit that in terms of measured efficency Ie: a flue gas test, may not come into play. Take two boilers at say 87% one cast Iron one Vitodens each 150kbtu. Most houses I'd have that in would have 4-10 zones. When only a couple zones call which is what happens most of the time that cast boiler is cranking out 150k to heat a 20k or 40k zone. The Vitodens will slow down as much as it can to minimize it's output, how much are we gaining while doing that? I'd say alot even though it doesn't equate to something you can read on your Testo meter.
The other potential savings is right upfront. I just came from a 12000sqft carriage house (yes really!). The exsisting boiler has a 14" flue to an unlined chimney that's 50ft high. With 82% boilers we'd have probably 5k$ in for a chimney liner alone. Put that towards a Vitodens, plus gas company rebates and I won't be shocked if the Vitodens ends up being no more exspensive even right up front!
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not true!
> Of course this only happens from a cold or
> ambient system start up. But we all know the
> that is far more frequent an occurence than a
> 180° all day long event!
This is absolutely not true. You may be stuck in a "bang-bang" operation mentality appropriate for cast iron. The boilers being discussed in this thread work in steady-state conditions by modulating the burner, which is more efficient than going on and off. So if 170 is required on that day by the outdoor reset logic, it will always be close to 170, and the return temperature will always be close to 170-deltaT, whatever that is. If it is going on and off as you describe, the water temperature is way too high.0 -
least?
> The least efficiency the W/M will get is
> 93%.
Irrespective of whether it condenses or not? I don't think so.0 -
huh?
> would be anytime it falls below condensing
> temperature at the return, say 130° F the
> efficiency would be in the mid or high 80's more
> like a conventional boiler. I'll bet a bb system
> designed for 180°F at design day sees a lot more
> than 10 days of above 130 return temperatures
> needed to keep it in 90% plus condensing
> mode.
What does all this mean? Maybe the world is flat?0 -
PDQ
guess that is confusing to read My point is that IF a condensing boiler is running with 170° return temperatures it is not in a condensing mode. Do you agree?
Also if the boiler is seeing return temperatures anywhere above the dew point of the fuel (assuming 130° for nat. gas) than the condensing boiler in not in the condensing mode. As such it will not achivee the 96% or whatever the max efficiency number the manufacture claims. ie Weil claim at 110-90° operating range (not a good range for hw baseboard, in my mind. Do you agree?
True the efficiency may be better than a bang/ bang cast iron, requiring 140 return temperatures, but I don't believe 10% better.
My next point is if the structure requires 180° supply to meet the load on a design day, which in Kens example may be 10 days in his area. There are days where the building could be heated with supply temperatures below 180°. But there is still a wide temperature range between a 170 return and a 130 return that a condensing boiler would not condense, if you agree with my above observation. SOoo until the return gets to the temperature where a condensing boiler condenses it will not be in it's high efficiency numbers. I would guess in Kens area that would be more than 10 days. Still with me?
No I am not a member of the Flat Earth Society, just trying to make sense of the condensing rage and it's real life efficiency numbers, and its place in high temperature systems.
hot rod
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System Heatup
Hypothetical system here:
200' of ¾" fin baseboard.
400' of ¾" tube or equivalent.
Water Capacity:
Approx 1.34 cubic feet in the tube. Let's be generous and say there's another third of a cubic foot (about 2½ gallons) in the boiler, manifold, etc. That give 1.67 cubic feet or about 103 pounds of water at a 140°.
Boiler Output (non-modulating): 96 mbh (based on output of b/b @ 170° assuming 20° delta-t, 180° supply)
Total flow, 10 gpm.
Hard to find output of b/b at really low temps, but if we're heating the system from 70° to 140° then the average temp will be 115°. Just for simplicity, lets say that the baseboard averages 150 btu/hr/ft output during the heatup phase--likely a very generous output figure.
Convert to minutes of time to make comparison easier.
150 btu/hr * 200' / 60 minutes = 500 btu/minute
Boiler 96 mbh / 60 minutes = 1,600 btu/minute.
103# of water must be raised 70 degrees requiring 7,210 BTUs.
After heat given off by the b/b, we have about 1,100 btu/minute left to heat the water. So after about 6½ minutes of fire the supply temp should be about 140°.
So you think, "Great, I get a reasonable period of time of high efficiency due to the low return temperature. But, I think there's still a problem. Condensing boilers don't only seem to want low return temperature to condense, they also want a decent delta-t to get high heat transfer to begin with...
The bulk of the BTUs are heating the water--both the supply AND the return.
Back to BTUs per hour for a moment. 96,000 BTUs from the boiler; 30,000 BTUs average given off during the b/b heatup.
30,000 / (500 * 10 gpm) = 6° average delta-t during heatup. You'll likely be recovering a decent amount of heat from the condensate, but your heat transfer to the water is likely to suffer considerably.
I truly don't believe that you're going to gain efficiency because of the heatup phase--in fact you likely loose efficiency.
Another problem with this scenario is that you're almost certain to be using reset with a condensing boiler.
Remember--you still have a digital system. ON-OFF only for the fire, the circulation and the space temperature control. Your heating cycles will be longer because of the lowered supply temp/lowered output. Consequently delta-t will be lower and your "cool down" phase will be shorter.
Now say your system is oversized (as most are) and you really only need water above 140° a small portion of the time IF it were CONSTANTLY being supplied.
At 140° average your output will be about 58,000 btu/hr. Your delta-t will be about 11.6°, so your return is still above the "magic" 120° mark because your flow rate has not changed.
What you need is proportional FLOW!
A couple ways....
Vary the volume of circulating water by changing the speed of the circulator. This sounds the easiest in theory, but it is difficult at present in practice.
Add TRVs and make your reset curve 10°-15° higher than required. This automatically reduces flow during maintenance conditions, increases delta-t and provides for rapid response to a call for increased heat. TRVs aren't especially easy to add to one-pipe loops. Even though the increased supply temp will result in lower flow and reduced return temp, the return might still be above 140° much of the time unless the system is well oversized.
Merely modulating the burner isn't going to change delta-t because it has not changed the output of the system.
Back to the originator of the thread. The Vitodens promises a "weather responsive" circulator. If you can bear the initial price, you should be utterly amazed at both comfort and efficiency--even with one-pipe, digitally controlled fin baseboard. That is provided that it was initially well-balanced and not sized by the "cover the outside wall" method. Noel gave you the link for sizing b/b systems. Make or get a good heat loss calculation as well. The more variable your climate and the more "oversized" your system the better for efficiency with this boiler!0 -
'nuther question Joel
I'm presuming that the control can also display the current state of circulator modulation.
Do you set for some fixed rate of the circulator?
If not do you see the circulator output change as valves zone valves open and close?0 -
Gas Company Rebates????
Sounds like yet another reason natural gas in my area of the country has gone through the roof to the point that winter electricity is nearly the same cost!
Utilities in MO (well at least mine which is big and in Illinois as well) does NOTHING to reduce consumption--no incentives, no anything unless done punitively. I do understand the problem with excess generation capacity in the winter due to our extreme cooling demand, but this is NOT market stability!!!!
5¢/KWH during the winter.
$1.24/therm for gas during the winter.
$1.00 worth of electricity gets 68,240 BTUs.
$1.00 worth of gas gets 80,645 BTUs.
At 15% loss up the flue, 68,548 BTUs per $1.00 of gas....0 -
180 degrees ????
> Mark,
>
> Most older homes have so much "fudge
> factor" in the heat loss that you will probably
> find that you have enough to handle your
> heatloss. So, before you put in any boiler do a
> load on the house.
>
> Then, as far as de-raiting
> your BBD. Standard BBD that puts out 600BTU/ft at
> 180avg will put out 500BTU/ft at 160avg. You can
> always increase flow and decrease delta T
> bringing up your average temp... but be careful
> not to exceed suggested flow in your copper or it
> could become noisy.
>
> Make sure to have a great
> air eliminator (like a spirovent) in the
> system.
>
> BTW - you can (with a little work)
> increase the temp on the Vitodens to 180 but by
> doing this you take the boiler OUT of condensing
> and thus greatly reduce efficiency (you do the
> same running the Ultra at 180F).
>
> wheels
0 -
180 degrees ????
Viessmann strongly suggests not to design any system above 160-165. per viessmann " unless you are god you will not get a supply temp. above 167 " only way i have seen this is when the boiler is air bound. even during domestic it limits itself. just a little info. marc0 -
i mean what I say
Marc,
Although I'd have to kill you if I told you all the details, you can go into a Vitodens and remove (physically, and not easily) a jumper on the board that will allow the boiler to run to 180F.
It is NOT suggested to do. It WILL reduce your efficiency. It will run the boiler over design, but still well within it's limits. If Viessmann suggested it and condoned it then it would be EASY to make the change.
wheels0 -
Do they have an incentive to reduce demand?
To what degree are utilities rewarded for managing customer demand? As best as I can tell, it is done by rebating energy-star systems to make them more affordable, which in turn allows the manufacturer to upcharge/value-price their offerings accordingly. However, does it reduce demand?
As best as I can tell, no. For example, the electrical company does not require you to dispose of your old fridge to get the rebate. Thus, many fridges end up as "extras" in the basement. The energy-star rebate thus just increased the demand for electricity sinced there are now two fridges in the house instead of one. Ditto for window-shaker AC units and the like. I wish the rebate was only granted when inefficienct systems are actually removed from the system, not reused at the same home or resold into the broader market.
Furthermore, we also run into realism problems. You can't achieve more than 96%+ efficiency, even with a condensing boiler/furnace/etc. So, as long as the trend towards McMansions continues, there is going to be increased need for fuel to heat those places. In most of the country, natural gas is the fuel of choice since traditionally it was cheap and gas-fired furnaces dominate the heating business and have a low installed cost.
However, the trend towards gas-fired electrical plants has changed the dynamics somewhat, particularly in areas like the NE where we are at the end of a very long straw that starts in the Texas panhandle. In MO and IL, I suppose you guys are close to the big coal-fired electric plants in the midwest. Hence, the ludicrously low electricity prices - In Boston we pay $0.10 pr kwh and about $1.35 per therm the last time I looked.
Lastly, I do not understand why the regulators typically approve very progressive gas and electrical price rate structure, where large users get a big price break while small users pay very high kwh/therm prices. Why incentivize large users to be less efficient than they could be?0 -
No rebating programs for Energy Star around here (unless it's built into the price of the appliance). I believe they do have some in Illinois, but not MO.
Couple good sized nuclear plants in MO, and lots still comes from the Tennessee Valley Authority (cover story was that TVA was to "electrify the rural areas" but it was mainly for the Manhattan Project). Summer electric is significantly higher, about 8¢, but still a bargain compared to some areas...
A few years ago (after being bought out by an Illinois firm) utility changed billing practices in a way they said would reduce charges to consumer. After operation for a few years and review by public service commission, they found it resulted in nearly $100,000,000 in excess profit. They got a token fine, had to put another token amount into the "help for poor people" program and subsidized a few 100,000 compact fluorescent bulbs that sold out within 2-3 days.0 -
So why did you say exactly the opposite in the original post I quoted above?0 -
Not true?
What temperature do you think the return water temp will be on start up and until any of the heated water makes the round trip?
It makes no difference whether the burner modulates or not!
A cold start is a cold start regardless of firing rate!
The 170° you suggest as somehow being the "norm" is anything but.
The number of days that 170, 160 or even 150 would ever be required are less than 1/2 the entire heating season. And during that time there will be many dead cold starts as well as the dominant periods of both fall and spring.
"Bang bang" boilers as you call them are no exception. All boilers will be cold startin most of the time. If a boiler operates at 98% efficiency for the first minute, then 96% the next one and so on. What do you think the average efficiency is for the total five minute "on" cycle that dominates the typical operation of the heating system in the vastly more common fall and spring weather the boiler will operate?
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No the control does not show the speed pump.
You have to set the min.and max speed on the control and the control picks the speed it should be at for that heating degree day. The pump and boiler are almost noiseless so it is hard to tell what is doing, it just does it! That pump is only on the two small boilers.
Ted
Viessmann rep.0 -
Need to Pick your Brain, Ted...
"You have to set the min. and max speed on the control..."
Regardless of the use of the low-loss header? (I'm guessing yes but you never know...)
"...control picks the speed it should be at for that heating degree day"
Does it learn which speed based on system in which it is installed or is it a fixed algorithm?
-----------------------
Still wondering about the use of low-loss header on my gravity conversion system with TRVs. Extremely likely that flow through the sytem itself (secondary side of low-loss header) will only be in the 1.75 - 3 gpm range vast majority of the time.
Unless the brain guarantees that primary flow is lower than secondary flow it would seem that the burner would start cycling because heat supplied by the boiler will start exceeding the heat consumed by the system.
With a really low "max" setting of the circulator but during a period of significantly higher secondary flow (say setting up a few TRVs), it would seem that the burner would start cycling on its high limit due to excessive delta-t.
Can the built-in circulator (no low-loss header, ONLY the Vitodens circulator used) deal with the heat-up phase of a system containing approximately 200 gallons at approximately the restriction supplied by a ¾" Danfoss TRV in "wide open" condition and 6' or so of ¾" piping from boiler to mains? (Once in the mains, low velocity due to small circulator volume will show essentially zero restriction to flow in the system piping.)0 -
On the 6-24
I recall the max head as being about 6-6.5 ft.
As I have been told and understand, in coding level 2, 045, you can set the max speed for the circ based on a percentage of 1-100%. From there the control tries to hit it's target Delta T by ramping both the pump rpm and the burner firing rate up and down. That's what the distributor rep told me but I would really appreciate someone from Viessmann chiming in here to confirm, deny or correct. The control is adaptive. It will "learn" your system and how to maintain what it wants to see.0 -
Flat Earth and Cast Iron
I hear exactly what you are saying Hot Rod. For all practical purposes, given a system that demands >160* supply, I am not convinced that a condenser is worth the extra dough, maintenance and service issues a lot of them present. Even if, as some claim, their boiler condenses at higher temps, I'd dare bet that the efficiency would be less than 5% compared to a good modern design CI unit.
Call me old fashioned but the only time I really wholeheartedly recommend any condenser is on a low temp system. Bear in mind that conventional heat emitters can be sized to provide that scenario as well as radiant floor type applications. I have done several panel rad jobs that require 140-150 max at design and they have condensing boilers on them. Many older homes also have drastically oversized BB, standing iron or whatever due to tightening of the building envelope.
I still think that aluminum is a questionable choice for HX material here in the "maintenance free" USA. All of these originated in Europe where thay take their maint a tad more serious than 95% of the homeowners on this side of the pond. I'm not putting any of my customers eggs in that basket for a while yet. If water quality is maintained perfectly, no problem likely. But how many folks here are even aware that it can be an issue let alone something that should be monitored?
All of you reading this may now call me all sorts of derogatory names including, Old fashioned, Stick in the mud, Backward country hick, etc. etc. My customers and myself have been burned more than once by "The Next Big Thing".0 -
We the contractors
got exactly what we have been asking for, and I thank all the manufactures that heeded the call for radiant specfic condensing, modulating boilers.
It will take years for them to "shake out" and we will discover the brands that get factory support and training, admit mistakes, and CORRECT them, always ask for installer input, etc. No doubt some will fall by the way side. Hard to tell at this point which are going the long run. Even change of ownership or staff can change the whole picture on the manufactures side, regardless of the product. Hard to forsee that these days
I'm not 100% convinced the low mass, low water content condensors are the best choice for high temperature BB, fan coil or indirect service. I don't see many 30 year old copper tube boilers in service, residentially speaking Only those with proper and adequate maintenance survive. Cast, gas fired, take a lot more neglect and whine less while doing it
Cast iron, especially with the ongoing upgrades, still has a big place in the hydronic market, in my opinion. As you mentioned reliability, cost and frequency of repair is hard to question on a cast boiler. Factor in the cost of service calls, replacement parts, and potential downtime for special OEM parts found on all condensors and cast iron still has some big advantages. As you too, Steve, have found, especially in rual areas. The cost of a warranty callback is getting higher all the time. 2 3 or 6 of those sucks the profit out of a job quickly, and can put you in negative numbers in cases. Think we have all been down that road
The main thing is we have some excellent choices out there currently. Pick the one that best suits you and your customer best. It is time to take the condensing plunge if the application fits, and you haven't already.
Make sure your eyes are wide open when you search the options. Now where's my hydronic crystal ball gone off to?
hot rod
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I'm amazed at how quickly we throw the
baby out with the bath water!
Most of you guys forgot about the obvious! That water heater in the basement next to the boiler! With fuel oil and natural gas approaching $1.40/MMBTU's - and no end in sight, all those fall and spring days of only needing ~120° water, and the incredible savings with indirect water heaters that last "forever" (instead of five or ten years) makes all condensing boilers an absolute home run.
Ever had teenagers taking showers? Ever had a lot of wash because you get dirty and so do your clothes?
There is no excuse not to use a condensing boiler on anything (except steam) - period.
Hell, I know someone who heats his desk with his boiler (:-o)
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And furthermore...
75% of the jobs we do already have double the HWBB they need because most installers just put baseboard on ALL exterior walls! Guess what the design water temp needs to be with THAT design?
Then we have the 1950 home where the double hungs were crap, the convectors oversized by a factor of 25% at least - and in 1985, the guy put 12" of insulation in the attic/cap, blown insulation in the walls - and Anderson double panes throughout.
The design water temp on the coldest day is now about 150°!
You guys been hittin' the sauce again?
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no babies or bathwater
being tossed here
I have been installing condensing appliances since 97. And servicing them. I'll still offer them.
I'll be yanking a 97 vintage condensor this week after 15- 20 service calls. It's getting a cast iron replacement with an indirect. Owners had enough R&D experiences, mostly on my nickel. 80 mile round trip from my shop is probably why it's been so problematic I doubt that it has saved him 3 grand worth of LP over that life span, which is what it cost him in 97.
Heck I've burned over 50 gallons of diesel in my truck on callbacks. Add that to the cost of operation!
Manufacture has been very helpful, warranty (5 year extended purchased) ran out as well as customers confidence.
My point is there is still a place in my company for a tried and true, easily serviced cast iron boiler.
The customer thanked me for all the "freebie" repair time and callbacks, and is taking the $3500 replacement very well, considering.
Buyer beware if you see a slightly dinged condensing tank type heater on e-bay next week!
Just kidding It will be a stainless steel "tin man" sculpture in my yard I suspect.
hot rod
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Can you share the \"brand\" of
your nightmare and a model?
Could you also describe what it is that drove the boiler to become a boat anchor in 7 short years?
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Yes, the control does learn the system!
over the years the control will know what it should be doing at that time of year or at that temp. outside. It takes at leased 32 start up's to know the best input to light off at. If it seems to cycle some at first, it will figure it out! If that pump has what it takes for your system, you could go with out the low-loss header.
Ted
Viessmann rep.0 -
That operation [might] change when the low-loss header is installed and the circulator goes into a different mode.
Vitodens really doesn't want a thermostat--you get a "warmer-cooler" dial. The end user is able to tweak the system to optimal performance based on his experience. Everything I've ever written about.
Please, please, please use TRVs or similar!!!!! Accurate heat loss. Radiation balanced depending on location/use.
0 -
I'm confused -
The last few posts have me scraching my head. It is my experience that the Vitodens is adaptive - but only within the parameters set by the programmer (me). It cannot exceed those limits even if the outdoor sensor indicates a very low temp and the heating curve is set incorrectly. Have I missed a critical statement re this topic???0 -
noel - is there an ETA on the SF baseboard charts
running at low temps - a lot of us are already sucessfuly running them under 120 - but we have no hard science - we are pioneering - holding my breath for your new data0
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