Heat loss by usage?

njtommy

Saw this on Mechanical Hub just wondering what you guys think.
http://mechanical-hub.com/hydronics/heat-loss-calculation-on-every-residential-boiler-replacement/

njtommy

I ran the numbers for my own home. I did it for the month of February. Manual J was 45,000 btus and this was right round 40,000 btus I would say its pretty darn close.

Robert O'Brien

Thanks for the input guys, I didn't think anyone would even read it!

Gordy

Very well written Robert. Makes it hard for anyone to use the method, and screw it up.

Robert O'Brien

njtommy said:

I ran the numbers for my own home. I did it for the month of February. Manual J was 45,000 btus and this was right round 40,000 btus I would say its pretty darn close.

The usage method is close to the Manual J or the other way around?

njtommy

@ Robert O'Brien Most of us are always reading and looking at different ideas and thinking out side the box.
Yes your really darn close. Lol you are correct in saying the usage is the way to go. Looking forward to reading more from you.

Robert O'Brien

It's certainly not perfect but I believe it is more accurate than a calculation based on factors that are most often just wild guesses.

njtommy

I feel that out door resets play a big part in this as well. Why heat up water to 160-180 if you don't have to or need to. Also knowing the customer where they set there heat at plays a hugh part in this for sizing. I set my t-stat at 68 all winter and don't touch it. If someone uses large temperature set backs I feel this these numbers will change too. The nice thing is you can look at your house and say yup we had 4230 hdd in February alone and I used 167 therms of gas and figure out how many btus you used roughly not including DHW or cooking. But a good average. At this point you could say hey maybe it's worth doing more insulating or something like that.

Also if your looking at doing a system up grade you can figure out how much is this really going to save me per month or per heating season and look back at the winter and say I spent $200 on gas and with a new unit it will cost me $150 for gas or oil. It's another tool to use.

Gordy

Hey Hat the way I see it when day time Highs are 65 ish the lows are probably 30ish 40 ish maybe 50 ish Enough days in a row of that mix, heat comes on most often. Its all depends on fuel costs at the time.

4Johnpipe

For a boiler swap it seems close. We are required to provide a heat loss for the energy programs and the building department records. Not that they know what they are looking at. However it does not take into account, cooking, clothes drying, how water or natural gas fireplaces. Also on multiple zones how does this formula affect the accuracy of some zones under working and some zones over working?
Example: I have a customer that has a simple 2 zone bi-level. They hardly turn up the lower floor if at all. There old boiler runs a long time shedding heat to the lower floor before satisfying the upper floor thermostat. Do I go with usage or perform a heat loss and suggest they keep the lower floor at 68?
I can see how it would relate to satisfy a single thermostat not how it would work well for multiple zones.

Robert O'Brien

4Johnpipe said:

For a boiler swap it seems close. We are required to provide a heat loss for the energy programs and the building department records. Not that they know what they are looking at. However it does not take into account, cooking, clothes drying, how water or natural gas fireplaces. Also on multiple zones how does this formula affect the accuracy of some zones under working and some zones over working?
Example: I have a customer that has a simple 2 zone bi-level. They hardly turn up the lower floor if at all. There old boiler runs a long time shedding heat to the lower floor before satisfying the upper floor thermostat. Do I go with usage or perform a heat loss and suggest they keep the lower floor at 68?
I can see how it would relate to satisfy a single thermostat not how it would work well for multiple zones.

The size of the pie doesn't change, no matter how you slice it. In your scenario, the usage system is vastly superior. Doing a Manual J you would count the lower level as heated space when in fact it may be more similar to an unheated space. What will that do to the calculated number?

4Johnpipe

Missing the point..aside form the goal of heating for "comfort" we have this oversimplified example. We have a client who has a 2000 sq ft home. They are older and live primarily on the lower floor. Trouble with stairs you know...They keep the second floor at 50 so pipes to bathroom will not freeze. They have a typical 80% boiler that fires at 100% every time its on. The lower floor thermostat will not satisfy as quick if the upper floor was set to 68. So the system runs for 15 to 20% longer at the full 160K BTU that boiler makes. It has to its loosing heat quicker to 1000 square feet of living space that is not part of the heated space (by choice I admit). I would offer that this would affect the history of usage reflected on the gas bill.

Robert O'Brien

4Johnpipe said:

Missing the point..aside form the goal of heating for "comfort" we have this oversimplified example. We have a client who has a 2000 sq ft home. They are older and live primarily on the lower floor. Trouble with stairs you know...They keep the second floor at 50 so pipes to bathroom will not freeze. They have a typical 80% boiler that fires at 100% every time its on. The lower floor thermostat will not satisfy as quick if the upper floor was set to 68. So the system runs for 15 to 20% longer at the full 160K BTU that boiler makes. It has to its loosing heat quicker to 1000 square feet of living space that is not part of the heated space (by choice I admit). I would offer that this would affect the history of usage reflected on the gas bill.

And how much is saved by keeping the second floor at 50F ? The usage is the usage. We're really splitting hairs,my point is there is an alternative system that is faster and easier and I submit more accurate than the standard system. If one is 40K and the other 45K, what's the difference? Are you really putting many 40K boilers in? I'm not,the consumer won't go for it. Everyone and I mean everyone has told them they need 140K, makes selling one 70% smaller a little tough,doesn't it?

Chester

I'm a homeowner who recently replaced my boiler and had the benefit of a professional Manual J to compare against an 'actual usage' heat loss calculation I performed myself, having learned about it on another website.

The house is a moderately insulated 1400 sq ft New England cape with forced hot water and 80,000Btu/hr of cast iron radiators (at 180F). The existing boiler was 140,000 Btu/hr (input) and cycled like crazy during the coldest days, so it was obviously oversized.

I used actual fuel use for December through March. It included DHW and cooking. During the period we kept the thermostat in the low to mid 60's so I ran the numbers at Base-55, Base-60 and Base-65 to give myself a range. My ASHRAE design temp is +2F.

My calcs gave me a high level of confidence that my heat loss is right around 30,000 Btu/hr (450 Btu/degree-hour). The subsequent Manual J performed as a result of a professional energy audit came in at 29,000 Btu/hr. Pretty damn close! And certainly accurate enough to help me decide between a 60, 75, or 100 Btu/hr gas-fired mod-con.

First contractor I spoke with wouldn't sell me anything less than a 110, which would only modulate down to my design day heat load. In my view that meant it would cycle more than I wanted for most winter days (average heat loss last winter was 19,000 Btu/hr). The next contractor wouldn't install anything less than a 75. Didn't want to take what he said was the 'legal liability' if I was wrong. I went with a Bosch Greenstar 57 that modulates down to 14 and a certified contractor that was happy to sell me what I wanted (once he saw the heat loss calcs).

I understand that professionals have to make lots of judgement calls when dealing with less educated consumers, so I get the 'better safe than sorry' approach, especially if the customer likes deep setbacks and won't tolerate slightly longer DHW recovery. On the other hand, it's hard to see the value of installing an oversized mod-con that won't take full advantage of its modulation capability, and even more so if it's hooked up to a system where you can't get return temps well below 130F to take advantage of the condensing efficiency. DOE might call these 95% AFUE appliances but you don't hit that until you get down to 100F return water temps. Above 130F they run at 85% or so, just like a regular on/off boiler.

Robert O'Brien

Chester said:

I'm a homeowner who recently replaced my boiler and had the benefit of a professional Manual J to compare against an 'actual usage' heat loss calculation I performed myself, having learned about it on another website.

The house is a moderately insulated 1400 sq ft New England cape with forced hot water and 80,000Btu/hr of cast iron radiators (at 180F). The existing boiler was 140,000 Btu/hr (input) and cycled like crazy during the coldest days, so it was obviously oversized.

I used actual fuel use for December through March. It included DHW and cooking. During the period we kept the thermostat in the low to mid 60's so I ran the numbers at Base-55, Base-60 and Base-65 to give myself a range. My ASHRAE design temp is +2F.

My calcs gave me a high level of confidence that my heat loss is right around 30,000 Btu/hr (450 Btu/degree-hour). The subsequent Manual J performed as a result of a professional energy audit came in at 29,000 Btu/hr. Pretty damn close! And certainly accurate enough to help me decide between a 60, 75, or 100 Btu/hr gas-fired mod-con.

First contractor I spoke with wouldn't sell me anything less than a 110, which would only modulate down to my design day heat load. In my view that meant it would cycle more than I wanted for most winter days (average heat loss last winter was 19,000 Btu/hr). The next contractor wouldn't install anything less than a 75. Didn't want to take what he said was the 'legal liability' if I was wrong. I went with a Bosch Greenstar 57 that modulates down to 14 and a certified contractor that was happy to sell me what I wanted (once he saw the heat loss calcs).

I understand that professionals have to make lots of judgement calls when dealing with less educated consumers, so I get the 'better safe than sorry' approach, especially if the customer likes deep setbacks and won't tolerate slightly longer DHW recovery. On the other hand, it's hard to see the value of installing an oversized mod-con that won't take full advantage of its modulation capability, and even more so if it's hooked up to a system where you can't get return temps well below 130F to take advantage of the condensing efficiency. DOE might call these 95% AFUE appliances but you don't hit that until you get down to 100F return water temps. Above 130F they run at 85% or so, just like a regular on/off boiler.

Why would anyone suggest more boiler than the attached radiation,80K in your case? The DHW recovery issue can be solved with a larger indirect and operating it at higher temps,with a mixing valve,of course. Glad you got the right size boiler,you'll be much happier!

4Johnpipe

Robert I'm not trying to argue or split hairs. Just trying to understand. Believe me I have done enough "free" heat losses to know the time spent for no monetary gain.
I am playing devils advocate in the sense that I am also a licensed inspector and as some have mentioned the codes require a heat loss and so do the energy incentive programs.
I want to get educated when asked how the usage can be separated from the actual heat loss requirements of a building. Yes factors such as insulation and air leakage are assumed and built into most design programs.
I also used my vague examples of ways usage can be skewed. Take the PV programs for solar panel installs. Many people will leave electric on for the months preceding the usage audit so they benefit from additional panels. Then they drop back to normal usage and reap the benefit of electric credits.
General statistics put domestic hot water heating at around 20% as an average of the fuel usage. Which can be broken out with math as well. Or is that factored into the heating degree days formula?

Rich_49

Better question would be this Robert . Why would anyone even mention attached radiation and boiler sizing in the same sentence ?
If one uses your method in a home that had a right sized boiler that was of the cast iron species and was operating at an conservative 80% AFUE your number is still subject to a 10% < possibility for error .
Take into account also that manual J , as flawed as it is is required by many codes or you don't get a permit . Also take into account that the installed radiation may offer lower temp opportunities . Maybe the radiation is not adequate , we've all seen that one before . You must know that our industry is filled with idiots that won't even understand what we are discussing here .
i say your method is better than what many are doing or not doing while at the same time offer this . perform the manual J , do a room by room to optimize efficiency of the plant and the occupants comfort . If doing it properly takes you too long , I suggest you charge for it like many of us do . You'd be surprised how many will wait a week for you when you are the best in an area .
The industry has been pushing the need for a proper heat loss for quite awhile now , where have you been .
Remember this Robert , "price is only an issue in the absence of value ."
Doing it right costs money , so charge for it and stop doing a disservice . I say that it takes no longer to walk and measure while conducting a required in my opinion interview of the client and their wants , needs and habits . When you charge for this and deliver then you will be a heating contractor . Maybe you do not have time for this whereas i do not have time not to do it .
What if your customer is going to perform envelope upgrades ? Then you'll really be not living up to their expectations or maybe they'll still have a short cycling POS which you were supposed to eliminate . The problem with Man J is that everyone who uses it seems to get caught up in the program limitations . If they all knew about assemblies and real world values of assemblies and knew how to layer materials they could perform much better heat loss calcs , but that is another discussion .
It is a shame when homeowners such as Chester know more than the average heating contractor about the relevant minutia of systems . Remember this also Robert , the house is a system and what you are describing does not prescribe to that end .
Again , while better than what most do , it still is not right .

Robert O'Brien

I have no problem discussing differences of opinion and I don't know if it is intentional or not but your attitude is off putting. If you'd like to have a discussion ,fine but I won't be harangued!

Rich_49

Political correctness is not my strong suit Robert , I apologize . Being frank and cutting through the crap is . Sorry if i offended your seemingly strong sensitivities . Some discussions are just too controversial to not cut through the nonsense and deal with head on .

Can you please enlighten me on something I stated that may be a mistake ?

Robert O'Brien

Civility isn't political correctness! Moving past that.
1. It's not a panacea or the solution to every job but a quick, low cost way to get a pretty accurate number,no more,no less. If you don't like it don't use it!
2. 10% deviation? Have you considered the possibility that it's the other way around? That the usage number is "correct" and it's the Manual J that is in fact 10% off? Think about it.
3. The house as a system? Very familiar with the concept from BPI class. The usage system is the embodiment of the house as a system approach,it takes every factor in that actual house into account,not a theoretical house with infiltration and R factors that are nothing but guesswork.
4. Your scenario of envelope improvements? More guesswork,how do you know what the R value of a wall assembly is? You know the insulation was installed properly? You know the level of air sealing without a blower door test?
5. No method is perfect but using the actual consumption of a home over a known period of time with known degree days is much closer to accurate than guessing at some factors that no one is really sure about! If you were going to conduct a scientific experiment to determine the actual heat loss of a particular existing structure,how would you do it?
6. If Manual j is required by local code,then that is that. Our local utility offers rebates on 16 SEER and up AC units, a Manual j is required to qualify. Want to know how it's done? The contractor decides what size unit they want to sell then makes the Manual J coincide with that,looks great on paper though!

Rich_49

Robert .
i will not argue your points . Especially about contractors fudging numbers . fact is that they are constrained by the programs . But check this out , If the internet went down today and I could not use a program I could still perform heat losses and design properly , because I know how to read . Guesses , i don't deal with them , i know how to layer assemblies , I know that FG batts will sag ,I know that ccSPF will degrade I know that the best window or door is still a crappy wall , I do require blower door numbers as Josie T can attest to , and more than we have time for , I KNOW BUILDINGS my friend .
While you are in an area that does not yet require blower door tests and calculations ( heat loss) I assure you that it is coming to town near you very soon and everywhere for that matter . Energy efficiency is a hot topic and not one that is likely to disappear in either of our lives . Byb the way , it is written in the IECC , lots of states are adopting it .
The quick and dirty method you describe where you measure how much gas was used and try to extrapolate how much was DHW , cooking , clothes dryer usage is better as I stated before than what we have had but please make no inferences that it will cut it .
I re read my post and don't really see anything that I could call not civil . Disagreements happen , i did not call you any particular name , attempt to assassinate your character or insult you . I just rebutted your claims and tried to point some in the right direction because I think yours is flawed and that is all .
You mentioned 16 SEER A/C units as an example . I see it all the time . SEER is a funny thing , it's very efficient yet very bad in an oversized unit such as the ones you describe . they run for too little time and remove nowhere near the latent load that they should . then the homeowner calls someone , not unlike myself to see why they are ill , have mold and still have high electric bills I explain to them that the unit does the sensible load then shuts off on temp before the moisture is removed , you don't feel comfortable so you turn the temp down to be comfortable and use more electric . they would have been better off with a right sized unit at 13 SEER that runs and runs and keeps everything right . to those folks I offer this " have fun explaining that you are either dishonest or ignorant after I speak out of a witness box in court " Just a symptom of " what we've always done" .
My goal is to end that and make any contribution I can to restoring our integrity as an industry . teaching the right ways whether they take a bit if time or not is part of that .
End of the day , you'll do your thing and I'll do mine .

Robert O'Brien

"i will not argue your points"

That is my point!

4Johnpipe

Here are some pictures of a brand new home that has oversize AC. This is the first summer. All steel surfaces rusted...Builder did not like it when I told him the units were over sized...

Rich_49

The pictures of the house above are astounding at how poorly this industry has educated the front line individuals . A bit of background that touches on sizing also .

I performed a heat loss and hydronic design for this roughly 8,000 sf home . Mind you this is a very tight house . This house had a requirement of 98,000 BTUh at a Delta T of 65* .
We watched in amazement as 510,000 BTUh worth of single speed FHA units were installed . To the folks who have been responsible for educating I say , "STELLAR JOB" !

So what do you do when the prior years bills are not available for any number of reasons ? What if the bills are available but the folks calling you are interested in changing because the house does not heat adequately ? Better to get everyone performing a room by room as opposed to other methods , it lessens the chance for wrong sized stuff . When you do a room by room you can also make sure the emitters operating inside your system are correct . Designing is part 1 of a process , we should start there then deal with the rest of the re education .

Robert O'Brien

4Johnpipe said:

Here are some pictures of a brand new home that has oversize AC. This is the first summer. All steel surfaces rusted...Builder did not like it when I told him the units were over sized...

No defending over sizing by any means merely pointing out that it is commonly done even with a Manual J required! Nice house,except for the rust,I guess it stainless not
stain free?

Chester

Robert O'Brien said:

Chester said:

I'm a homeowner who recently replaced my boiler and had the benefit of a professional Manual J to compare against an 'actual usage' heat loss calculation I performed myself, having learned about it on another website.

The house is a moderately insulated 1400 sq ft New England cape with forced hot water and 80,000Btu/hr of cast iron radiators (at 180F). The existing boiler was 140,000 Btu/hr (input) and cycled like crazy during the coldest days, so it was obviously oversized.

I used actual fuel use for December through March. It included DHW and cooking. During the period we kept the thermostat in the low to mid 60's so I ran the numbers at Base-55, Base-60 and Base-65 to give myself a range. My ASHRAE design temp is +2F.

My calcs gave me a high level of confidence that my heat loss is right around 30,000 Btu/hr (450 Btu/degree-hour). The subsequent Manual J performed as a result of a professional energy audit came in at 29,000 Btu/hr. Pretty damn close! And certainly accurate enough to help me decide between a 60, 75, or 100 Btu/hr gas-fired mod-con.

First contractor I spoke with wouldn't sell me anything less than a 110, which would only modulate down to my design day heat load. In my view that meant it would cycle more than I wanted for most winter days (average heat loss last winter was 19,000 Btu/hr). The next contractor wouldn't install anything less than a 75. Didn't want to take what he said was the 'legal liability' if I was wrong. I went with a Bosch Greenstar 57 that modulates down to 14 and a certified contractor that was happy to sell me what I wanted (once he saw the heat loss calcs).

I understand that professionals have to make lots of judgement calls when dealing with less educated consumers, so I get the 'better safe than sorry' approach, especially if the customer likes deep setbacks and won't tolerate slightly longer DHW recovery. On the other hand, it's hard to see the value of installing an oversized mod-con that won't take full advantage of its modulation capability, and even more so if it's hooked up to a system where you can't get return temps well below 130F to take advantage of the condensing efficiency. DOE might call these 95% AFUE appliances but you don't hit that until you get down to 100F return water temps. Above 130F they run at 85% or so, just like a regular on/off boiler.

Why would anyone suggest more boiler than the attached radiation,80K in your case? The DHW recovery issue can be solved with a larger indirect and operating it at higher temps,with a mixing valve,of course. Glad you got the right size boiler,you'll be much happier!

Chester

Thanks Robert: I'm very grateful to you and others for helping me get educated about all this. Looks like I actually have enough radiation to run 130F water on my design day so I feel like I have a head start on where to set the ODR curve.

However, I'm still confused about whether to go with the new controls Bosch has (basically Indoor Reset) vs. outdoor -- or whether they actually work together. But I can obviously wait until someone has had actual experience with them in the field. A room sensor that can modulate the boiler seems to make a lot of sense with respect to managing solar gain, cooking, etc.

Robert O'Brien

Chester said:

Thanks Robert: I'm very grateful to you and others for helping me get educated about all this. Looks like I actually have enough radiation to run 130F water on my design day so I feel like I have a head start on where to set the ODR curve.

However, I'm still confused about whether to go with the new controls Bosch has (basically Indoor Reset) vs. outdoor -- or whether they actually work together. But I can obviously wait until someone has had actual experience with them in the field. A room sensor that can modulate the boiler seems to make a lot of sense with respect to managing solar gain, cooking, etc.

Unless you got the new floor mounted model,it comes with the FW200 control.

jonny88

A lot of credit for your article Robert as we all learn from it.whether it is criticism or positive comments but we all take something from both sides.Takes a lot of balls to put yourself out there so kudos.

4Johnpipe

Hatterasguy said:

Hatterasguy said:

Mr. O is absolutely correct.

Doing a heatloss room by room takes a couple of hours and is still fraught with errors due to the assumed infiltration and the assumed R value of the walls.

He's taking actual consumption and determining a heatloss based upon degree days. Far more accurate approach and it can be done in about one hour.

Also, note the point about the available boiler size on oil. Why bother with a heatloss if the smallest oil fired boiler you can buy delivers a net 71K even if you downfire it to a .5 nozzle (at 140 psi).


Excellent.

If you do a room by room heat loss and know the BTU's required for each room you may very well be able to lower the boiler temperature...or perhaps add some heat emitter...or both. Having the information opens up options that others may never have offered.

njtommy

I'm busy for two days and all hell breaks lose. Lol. @Rich @4Johnpipe that house is crazy. I can't believe that the steel rusted like that inside. My mind is blow after seeing that.

I will also say this. I've a chance to talk to Rich on the phone a few times. He's a pretty smart guy and I would have to say he's one of the best I've talked to in Nj.

Robert O'Brien

4Johnpipe said:

Hatterasguy said:

Hatterasguy said:

Mr. O is absolutely correct.

Doing a heatloss room by room takes a couple of hours and is still fraught with errors due to the assumed infiltration and the assumed R value of the walls.

He's taking actual consumption and determining a heatloss based upon degree days. Far more accurate approach and it can be done in about one hour.

Also, note the point about the available boiler size on oil. Why bother with a heatloss if the smallest oil fired boiler you can buy delivers a net 71K even if you downfire it to a .5 nozzle (at 140 psi).


Excellent.

If you do a room by room heat loss and know the BTU's required for each room you may very well be able to lower the boiler temperature...or perhaps add some heat emitter...or both. Having the information opens up options that others may never have offered.

So you can't use ODR without a Manual J?

SWEI

njtommy said:

that house is crazy. I can't believe that the steel rusted like that inside.

304SS will do that in a corrosive environment. The humidity would need to have a low pH, and quite likely contain sulfates, phosphates, or something "extra" in it.

4Johnpipe

Robert O'Brien said:

So you can't use ODR without a Manual J?

I'm pretty sure you can...It still remains ODR has nothing to do with what each room requires for BTU's

Robert O'Brien

4Johnpipe said:

Hatterasguy said:

Hatterasguy said:

Mr. O is absolutely correct.

Doing a heatloss room by room takes a couple of hours and is still fraught with errors due to the assumed infiltration and the assumed R value of the walls.

He's taking actual consumption and determining a heatloss based upon degree days. Far more accurate approach and it can be done in about one hour.

Also, note the point about the available boiler size on oil. Why bother with a heatloss if the smallest oil fired boiler you can buy delivers a net 71K even if you downfire it to a .5 nozzle (at 140 psi).


Excellent.

If you do a room by room heat loss and know the BTU's required for each room you may very well be able to lower the boiler temperature...or perhaps add some heat emitter...or both. Having the information opens up options that others may never have offered.

"If you do a room by room heat loss and know the BTU's required for each room you may very well be able to lower the boiler temperature"

By lower boiler temp, I assume you mean via ODR? And you can't run lower water temps without knowing the heat loss of each room on a design day?

4Johnpipe

Robert I was actually reffering to a standard oil boiler as was the original example...I was also assuming fin tube emitters (see attachment for output per SWT). By degrading an output on the oil boiler and knowing the exising footage of emitter we can lower the supply water if conditions allow to deliver the required BTU's to each room. I know most do not design a series loop system this way we do though. That said if you have gathered the information from a room by room heat loss I have found that most houses have more feet of emitter in each room. This would allow the designer to lower the water temperature and insure return water above the dreaed condesing zone.
Put all this together and it saves on fuel. Outdoor reset is great provided the emitter whatever is installed is accurate for each room. Then the boiler will modulate the supply water tempurature as needed for the heat loss to the home. The boiler doesnt know what each room needs it just knows what the structure as a whole needs.
I hope I am making sense typing thoughts out as they fly is not always as clear as whats in my head...
Believe me a know the time invloved in performing heat losses. I spent far too long doing it for free hoping my time and effort would convince the customer that I knew what I was doing. I charge for this and spend some time to show the value of why this is crucial, and in fact just picked up payment tonight for another.
This cutomer has 2X's the boiler size and has among a few other issues grossly over acceptable fuel bills. The reasons have to do with zones that do not have enough heat causing other sones to over run and basically his boiler now never shuts off. Thye always have zones loosing heat to other areas in this case mainly due to bad controls at the boiler..or I should say lack of control.

Robert O'Brien

We do replacements, rarely new systems. I should have clarified that. And of course you need a conventional heat loss on those. Let's assume we're replacing a tankless coil oil boiler with a triple pass boiler,indirect and reset control into a two zone baseboard system colonial, 2000 sq/ft. You do a Manual J, I do the usage method. You come up with 50K,I come up with 55K so we both pick the smallest available or 75K. I don't know what the room by room is,you do. They removed 6' of baseboard when they remodeled the kitchen, you find they are now 3' short in that room but over in every other room, I don't know that. Not going to run temps under 140* to protect our new boiler from condensing, I think we can both agree on that? With this knowledge,how do you set the reset curve any differently than I would?

4Johnpipe

Sorry I wasnt talking about setting a rese
t curve...What ODR control are you using? I was talking about derating the BTU output on the oil boiler that Hatt was talking about by way of a smaller nozzle. I also dont install much oil. Take quite a few out though...We use Taco VDT circulators exclusively. With these we can set the system supply and return to a fixed DT of our design. Baseboard is typically 20 degrees. This way we can set the high limit on a conventional type boiler as mentioned to say 170 out which brings back 150 through the series loop.
Of course we couldnt do this unless we know the BTU output of the emitters using an average water tempurature of 160. We also would need to know the characteristics of each room with heat to confirm that the amount of emitter is able to provide the lost heat.
We also install HTP products almost exclusively now. These all have the ability to set a maximum BTU or derate the boiler as well if needed.
Aside from all of this the usage method seems like a quick way to get the bid out. You certainly could not get hurt. Perhaps after the job is won you could perform the Man J and tweek the systems for "improved" efficiency possibly as and upsell.
Lastly the codes in NJ do require a Man J heat loss even for a boiler swap out and so do the rebate / incentive programs we use that are in place now.
Just installed an HTP EFTC-140F and will tweek it after the combustion analization is completed.

ChrisJ

I've found the heatloss in my house is around 72,000 btu/h with an ambient of -8F and indoor temp of 72F by using the EcoSteam.

I too, am curious why "stainless" panels on appliances would rust? None of them seem cheap by any means and even my kitchenaid appliances doesn't rust if left soaking wet, forget about in a damp room.

jonny88

@4Johnpipe thanks for posting pic.A picture says a thousand words.I am going to try to start using this product after numerous conversations with Rich.I have a closet install can I use chimney as a chase for both exhaust and intake and terminate on roof.Hatterasguy like unit to.What unit do I use for both heat and hot water.It might be worth my while to take a trip to Emerson and see the products.Did you see in Wisconsin they are using HTP exclusively on a new University.Sure looks like you are onto a winner.Thanks.

RobG

@4Johnpipe, I think that I need not ask, BUT were you not done when the photo was taken? The gas pipe looks to not be strapped and the abandoned oil line is still present.