Do condensing, 90%+ boilers always condense?

Steve McCarthy_2

I have a customer that wants to replace his existing boiler with one that is higher efficiency and has shown interest in a condensing boiler (90%+). The house is a nice old one with baseboard convectors and three zones. The walls are blown with cellulose and the job is so..so typical. A friend did an IR scan and I did a blower door test. While we can improve the insulation a bit and tighten it up, It still won't be a high performance house. If the baseboard convectors need say 160 degree water to heat the rooms and the water returns at 140 , how much condensation will really occur. I can understand that high efficiency works best with low temp radiant floor heat, but can it work in an older house with baseboard. I know the system will work but will it work at 90% efficiency??
Thanks in advance to those of you that take the time to respond with an explanation. Steve

Steve Ebels_2

If

If you use a reset system on the boiler, you'll likely see condensing temps for most of the heating season. Supply temps of 160-180 are usually needed at "design conditions" so the rest of the year your water temps are substantially lower. Run a heat loss on the house and use an outdoor temp of 25* for example. You can see from those numbers that you'll be able to meet the heating load with a lot less water temp than normally used. Combine the reset with a modulating burner and you typically have some pretty nice fuel savings on your hands.

Plumbob

No, they do not always condense. Above ~135F return temperature there is no condensing at all. Plus, the efficiency doesn't suddenly jump when the return water drops to 134F; rather, the efficiency increases slowly as the return temperature is lowered. The AFUE rating is based on quite low return temperatures.

This does not mean that a condensing boiler never condenses. You MUST use outdoor reset to lower the water temperature as much as possible; this also means more comfort and less noise. Baseboard does not have to operate at the same water temperature in all weather. However, generally there is not an excess of baseboard, so the house may need 160 or even 180 (supply) in typical winter weather. In that case there is no condensation until the weather warms up. Plus, baseboard output drops off rather sharply (not linearly) as the water temperature is lowered, hence it is not an ideal candidate for savings with reset+condensing.

On the other other hand, maybe this house does have lots of baseboard and can run most of the year under with 140F supply temperature, in which case there is no problem.

Kal Row

he WILL save fuel...even with a non condensing load...

Above 136the flue gases wont condense, so any time the return temp is above 136 - you cant extract all the heat from the flue gases so it’s "non-condensing" at that point, - BUT!!! - the combustion on these types, is much more efficient - and they modulate to the load, and they will drop the system temp on a warmer day, ie if it's a 50f night, it will run the baseboards below 136 - and yes, they still work at that temp, just a lot less btu's per foot

So: I recommend go for the condensing boiler – like a Weil-McLain ULTRA – which handles those types of loads with aplomb – experience with many here on the wall bears this out – there is at least one guy out there we know of, that connected a WM ULTRA to an old cast iron gravity system and is saving money – so there – over the next year, you will see a lot of aluminum HX condensing boilers coming to the market

Reynz_2

Working well for me

It has been working great on my gravity converted, baseboard system. Overall, as most have pointed out, my WM Ultra heats my house with less than 140* water. It has to go to the upper to mid 20s for my boiler to use more than 140*. So far, 95% of this winter weather, I have benifited from lower temps, and received the most from my Ultra.

I finally have it set up properly and I (from one who watches temp every day) can tell you I see absolutly no fluctuation from the temp I set on the thermastat. If I set it on 71*, it stays on 71*. Since I use a tighter reset curve, constant circulation and a set temp of 70 at night to 71 during the day, I've been as happy as a Wally at Wetstock. (Did I say that correctly?) Questions, Let me know. Reynz

DaveGateway

Some 90%'s

like the Dunkirk Quantum Leap, claim to condense even with 140° return water once it passes through a secondary heat exchanger.

Kal Row

let me get this...

the return water is lets say 150, and the flue is 140, why wont the return water lose heat to the flue gases? - and if the return water is above 140, against what are they condensing it? Maybe they have and air-hx and are preheating the combustion air with it, hey: on the vie$$mann vitodens 200 they are recovering all the radiant heat from combustion!!!, so who knows…

on the ultra - they modulate the burner and the fan - so that you at least dont lose return water heat - it was designed as a broad range product - another manufacture i know coming out with an aluminum hx boiler is targeting the same audience

Reynz_2

To Condense or not to Condense

Kal, A nagging questing from a Novice, is this "Does it or does it not condense" really the question?

These are my basic thoughts.

A Cast Iron boiler needed to run water temps above 137* through the boiler loop all the time, no matter what the outside temperature was, to prevent condensation from collecting and causing that nasty caustic gas/water stuff from corroding the -------- something. Correct?

So, any time I'm heating my home with input water temp less than 137* I'm already batting a 1000 because I'm doing it at a lower temp than the minimum that a CI boiler had to run, correct?

The condensation benefit is really only a secondary byproduct of the condensing thing, but not the real reason. Really, how much of a benefit does one get from sucking the last bit of heat from the return condensation drippings anyway???

Tony_8

Condensing temp

Whether a boiler is condensing or not doesn't depend on the supply temp to the emitters, it depends on the return temp. I have a bbd system with an Ultra driving it and the heating lmit is at 140F supply. We've had design days w/o a problem and I know the original install was designed for 180F. Even when the DHW is calling at full fire and temp capabilities it still condenses some. The big key is the heat transfer rate of the aluminum block and the modulation of the flame.

Reynz_2

Condensing Boiler

However, any time I'm heating my home with input water temp less than 140* I'm already batting a 1000 because I'm doing it at a lower temp than the minimum that a CI boiler had to run, correct?

Ron Schroeder_3

Whether a boiler is condensing or not doesn't depend on the on the return temp either, it depends on the flue temp and the fuel type. With oil it is 115 degrees. It is slightly higher with LP and nat. gas. One big advantage of a condensing boiler is you don't have to worry IF the boiler does condense even if most of the time in a particular installation it doesn't.

The real question isn't if a condensing boiler is cost effective compared to an old boiler but is a condensing boiler cost effective compared to a modern non-condensing boiler. You have to weigh the fuel savings against the higher purchase cost and higher maintanance cost.

For radiant floors, it's often a win for condensing but for baseboards, even with outdoor reset, the break even point is often longer than the equipment's life.

Ron

jbplumber

Modulation

Suppose his system does run at 160* or even 180* currently. The key thing is to get an idea about what the average water temperature is in the circuits over the course of a day. That's where the truth will lie about its ability to condense most effectively. If the boiler runs 7 hours on a normal winter day taking the system up to 160* and the rest of the day the system keeps falling back and occasionally reaching a room temp of 70*, you may find that a modulating boiler would be able to keep it heated at a temperature where it is condensing.


You could also consider ways to add more emmitters in the house to get the return temperatures down even more.

Floyd_7

Why is it always about money?????

I could name many reasons other than money to buy a condenser.......

NUMBER ONE.... can anyone say COMFORT!!!!!!!

Heatmen need to go to school with some car salesmen.....

Floyd

Darin Cook_3

Here is a fact produced by a customer

We installed a nat gas condensing boiler in customers home with a 40 gal indirect. The house is 4 zones of hot water baseboard (fin tube). They were always very happy and comfortable with the system. On the coldest day of the year the boiler will run at 190', on the very mild days it will run at 100'. We have another customer call about upgrading his 25 year plus utica boiler to a condensing boiler. We give him the the other customers name and address for a reference which they said was ok. He goes and checks out the install, was very impressed with the craftsmanship, gave us some constructive criticism, and asked to borrow the HO's gas bills for the last two years. That covers the old boiler for a year and the new boiler for a year. He makes his own spread sheet up and tells us the other HO had a fuel savings of over 37%. He then calculates that the new system for him would pay for itself in 6-7 years. Needless to say, He bought a new condensing boiler from us. The proof is there, a condensing boiler even with a hw bb system will outperform a standard CI boiler. The thermal efficiency of a condensing boiler is MUCH greater than a CI boiler. All of the said calculations were done by a potential customer, who wanted to make sure he was spending his money wisely. Not to mention, sealed combustion, zero clearance, modulation. All great benefits with a condensing boiler.

Darin

Tony_8

that

is a mirror of my experiences

Tony_8

It does when

The return is entering the block at the point of egress of the flue gases

Ive never had any success lowering utility bills on a heating system by replacing a well tuned, older, CI boiler with a new one of the same ilk. I've even had a nightmare job where the old wetbase out-did the new dry base under certain conditions (like design days).

Mark Hunt

Not just an isolated case either

The Munchkin boilers we have installed allow us to go back into the board and look at how the boiler performed.

With our laptop we can see the number of hours the unit ran and the percentage of the time it was below 50% firing capacity and above 50% firing capacity. In EVERY case the boilers were below the 50% capacity for the majority of the time they ran. That is because the majority of the heating season is not "design day".

Despite popular belief, copper finned baseboard does work with substantially lower water temps. Where is it written that 100* water will not cause convection through baseboard? On a 50* day that may be all you need, and it works.

This "on or off" mentallity does not hold up when compared to reallity. By "on or off" I mean "180* or nothing". If you watch a baseboard heating system connected to a fixed-fire boiler in October or November, you would see two things. First it would short cycle, and second it would not reach 180* much less 160*.(Unless you live near Weezbo)

Referring to these systems as "high temp" is only accurate when they are operating at design day. Baseboard and CI rads were sized for worst case scenarios with maximum HWS temps. How they would operate during milder days was never considered. Nearly every piece of literature you look at concerning a hydronic heat producer, i.e., baseboard, indirect etc.., are based on Max water temp for max recovery or output.

Remember, the Dead Men sized cast rads to heat rooms with the windows open at one point, and some of their great,great grand children are continuing that practice today!

Mark H



To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Constantin

Totally agree...

... unless the distribution or the emitting system has some serious issues (in which case it probably wouldn't work with a CI boiler either), design day conditions will predominate about 2% of the year. A whole week...

The rest of the time, the boiler will see less than design-day conditions. During these days, a properly set-up and piped system will enjoy much lower water temperatures and much longer run-times thanks to modulation, outdoor reset, and possibly constant circulation.

This is the one caveat that ought to be mentioned: unlike the boiler swap we heard about in DC that involved a Vitodens being put in by the low-bidder, "a boiler is NOT a boiler". A condensing system may require some re-piping around the boiler to maximize the extent to which it can take advantage of constant circulation, better thermal control via mixing valves, etc.

All of these factors will lead to greater fuel efficiency, comfort, etc. yet have nothing to do with the boiler itself. Furthermore, some of them are features that cannot be used on a CI boiler because most CI boilers need high return water temperatures while the condensing boiler loves to get the opposite.

Lastly, it is dirt cheap to add some panel rads, etc. to rooms to increase the surface area of their heat emitting surfaces to the point where the room will get heated on a design-day, even with a 140°F supply water temperature. However, even if this is not done, the reality is that 90%+ of the time, a condensing system will be condensing.

And as others have pointed out, I wouldn't even start by looking at arbirtrary numbers like the AFUE because the AFUE does not take start-up, shutdown, or standby losses into account. The proof is in the pudding when a 94% AFUE boiler replaces a 80% AFUE boiler and the fuel consumption on a corrected degree-day basis drops 40%.

Here, non-AFUE-related factors like low boiler mass, modulation, and the control and distribution system work in harmony to produce and distribute comfortable heat very efficiently.

Kal Row

i have been too busy...

“Condense or not”: load matching freedom, puts the vote overwhelming for condensing, and on some loads, it’s huge, eg: radiant in a concrete slab under tile, where the supply is 110 and the return is 90, the ultra gets to 98% on those loads!!! The others are only 2points behind (chalk it up to aluminum’s lowest mass and heat exchange speed – saw lot of vendors with, or coming out with, aluminum at ISH), now, on a Cast iron boiler, you would need primary/secondary/variable speed injection to get the boiler loop to temp quickly, after that, when the heat demand goes away, and the damper closes, you are now dumping the heat into the room – which you may or may-not be able to use, so you really need an indirect domestic hot water tank – where you can purge the boiler’s heat to, when the demand goes away, and the boiler is above 120, – and only if you do all that, do you have a hope, of getting it’s rated efficiency all the time, most CI setups are running closer to 45 avg, whereas on a modulating and condensing boiler – you are starting at 80 – and there are very little losses on a hot turnoff and none if you have an indirect – forget AFUE ratings, they are like statistics – and prove the old adage, statistics tell where the truth “lies” – but that’s a whole nother thread

“Combustion efficiency”, both the munchkin and the ultra use the venturi mixing gas valve and the associated combustion chamber where the mix is burned as close to perfect as possible

to sum up:
load match freedom, combustion efficiency, and freedom from flue draft and induction air issues, skyrocketing fuel costs, all make the choice overwhelming in favor of condensing boilers – no matter what your load is – the person that installed “Reynz’s” ultra – originally put it in all wrong – and yet it was still saving money – and it is a cast iron gravity conversion load, talk about load-match freedom!!!, peer pressure from “the wall” with some green stuff from “Reynz” has since gotten the install corrected

ps: for you oil consumers, I have no personal experience with the monitor FCX condensing oil, but there is a recent thread on the wall

Reynz_2

Thanks Kal

Great Job Kal, and Floyd, yes I'm enjoying great comfort.

Bottom line, I believe I have received a tremendous education on the wall, especially from Floyd and Kal, and others about condensing boilers. I am very happy with the performance on my CI BB Gravity Conversion System with the Ultra, can see the benefits both with comfort and $$ (sorry Floyd). Would do it again. (HOWEVER, the company I originally chose to install it knew ABSOLUTELY NOTHING ABOUT IT). My settings were not changed to maximize efficiency based on my particular situation and I had temperature swings of 4 above to 3 below the thermostat, but I was still saving money. Now that it is set up properly, I am VERY, VERY, VERY happy, and my thermostat doesn't budge off the setting unless I change it.

However, I’m not thoroughly convinced that I will never see the monitory benefit of the savings within the service life of the boiler. I believe I will.

Steve Ebels_2

Modulating BB temps

I have found that running BB at low temp works and works well. Maybe you remember the project of ours that Dan did an article on in PM Engineer. It was 3-4 years ago and it tweaked him because we used a two pipe pri/sec piping system. Look it up in the PM archives under "It just made sense".
The system we installed there consisted of a 2 stage Buderus CI boiler driving 6 zones (apartments) of BB plus DHW for the whole building. We used the 2107 Buderus control for resetting the water temps in the boiler and system and after a little fine tuning of the curve, the circs run nearly 100% of the time. As most here know, the 2107 on a CI buderus will allow the circs to run all the way down to 104* before shutting them down and firing the burner. This is almost the same effect as a condenser minus of course the modulation. The thermostats act only as a high limt for room temps.

Anyhow, this building is approx. 7,000 sq ft., new construction, well insulated and houses 6 families. To date, even with nat.gas costs over double what they were when installed, they have yet to see a gas bill over $400 for a month. To me, this is outstanding considering it's also supplying DHW for an average of 16-18 people everyday.

I sized the baseboard maybe 10% over what the heatloss indicated. This would probably be typical in most homes a person would run into. It just flat out works, I don't care what the charts say about BB falling off steeply at lower temps. Look at a heat loss for any given house and you'll see that the heating load is not linear either.

When I figured this job out, I made a graph in 10* increments of OD temp and plotted the corresponding heat load and the BB output alongside of it. The two lines nearly match.

The point of this little essay is not to state that a CI boiler is the equivalent of a modulating condenser. Good ones, that can directly take low temps and are installed properly, are close, but they can't match what a condenser will do.

What I have proven from my own experience on this job is that BB will heat well at lower than normal accepted temps. Also that the ability to directly modulate the boiler temp itself is a major factor in energy cost reduction. This last statement is in sharp contrast to merely installing a mixing valve and modulating the water temps going out to the heat emitters while leaving the boiler at 160-180 all the time. To me, there is little advantage in that other than longer circ run times.

BB on low temp works.

Gotta go calm my lab, there's a squirrel on the bird feeder and he's going nuts.

Have a good day !!

Kal Row

pay it off in a lot less than it's life..

the ultra install is apx 3.5grand more than the equ CI – and if the CI is done P/S/injection then it’s still apx 2k more (I am thinking my trade cost for the raw boiler only)

you are already saving apx 50-100 per month, so you pay it off in about 3yrs and faster still if the gas goes up at the projected rates – that’s a fraction of the guaranteed HX life

Darin Cook_3

A tid bit of info

I was doing a clean and tune on a condensing boiler today. I was getting 196' on supply temp, 175' on return temp and 150' on stack temp. According to the general impression that should be impossible. That was for the indirect. The heat was calling for 130', stack temp was in the 90's. How do you think that figures in fuel savings?








Darin

Kal Row

excess air, keeps the stack below pvc danger levels...

but you are not condensing the flue gases, and you are really supposed to use CPVC or stainless

in the future they will be using the higher stack temps on hotter loads for electrical co-generation

also even today on the monitor fcx or the buderus
they have different load loops, so you can for example, use the final stack heat extraction loop for a cooler load like slab radiant, or even have another low temp indirect tank to preheat the cold water coming from the street before it gets to the main indirect tank – I cant understand – why all condensing boilers don’t have dual return and discharge ports, and that except for cost – why everyone with condensing boilers, and mixed load temps isn’t doing dual lo hi indirect tanks – instead of cooling the stack with excess air

another thing they can do with a hotter stack, is, use the vacuum boiler tubes like they have in the new solar collectors to concentrate the heat, – ie the law of the lever works with heat too – you can exchange distance for force – or a large area of liquid boiling off at a low temp in a vacuum tube at one end, to condense into a much hotter but smaller area at the other end, by latent heat of condensation, where a flowing water jacket takes the heat away – sure the total btu in and out is the same, we are not creating btu’s, but the output temp is now matched to, thus imparting whatever few btu’s were input, to the higher temp load – at ISH they had one on demo, where there was a tube, with a spotlight on it, and it was just a little warm for most of it’s length, and at the other end, the condensing bulb was to hot to touch, – so instead of solar glass vacuum tubes – they make stainless ones, and stick them everyway from flues to clothes drier outlets – with mass production they should be cheap – we haven’t even scratched the tip of the iceberg – when gas is 10 per gallon – we will wake up and utilize the technology we already have

there – you guys got me started again…on one of my energy waste tirades


actually for cloths driers – the Chinese already have a better mouse trap – they make a washer drier combo that uses a compressor and coils to heat the water for washing, and for drying, they recirculate the air in the box, and the air coming off the hot condenser flows over the cloths to dry them, and then flows over the cold evaporator to extract the moisture – which is pumped away as needed, = so you only take up the space for one appliance, and you don’t have to move the cloths, and all you need is a power, cold water and drain – you can buy it here from HIER electronics LLC, but we wont, cause a regular washer and drier here, is half the price and we would rather indirectly feed the terrorists, wouldn’t we??? – told ya, “don’t get me started”

Plumbob

Plumbob

> It just flat out works, I don't care what the

> charts say about BB falling off steeply at lower

> temps.


Our house has radiators, plus a small newer extension with CI baseboard. At 180F, the run times are the same. At 130F, the baseboard zone needs over twice the run time that the radiator zone needs. Just the facts.

Tony_8

how

Do you get that much excess air when you have a flameholder like the Ultra ? Wouldn't it blow the flame right off the cone ? The excess air statement doesn't make sense to me.

Kal Row

you are correct - it would have to bypass the flame somehow

dont know exactly how they do it - but the fan speed modulates down with burner when return temps are low and demand is low

Darin Cook_3

Kal, I don't follow the excess air statement either

In the case of the boiler I was talking about, the fuel and air mix prior to the burner with a venturi effect and the flame burns in a 360' pattern. How much excess air can you push through that and keep the flame on the burner tube? The point I was trying to make is that the thermal efficiency of any of the condensing boilers out there is much higher than a standard CI boiler. Now if you were talking a power vented water heater you are correct, it pulls a massive amount of dilution air out of the room so the pvc will not melt as it vents.






Darin

Kal Row

ok, whn i get back to office i will find my wm person & email

could not figure it out from the pictures - maybe floyed knows - he has more ultra experiance here on the wall than anyone else

Steve Ebels_2

True

Blending a system is difficult to say the least. Careful calculation is needed to ensure that it will work and sometimes, depending on the amount of each type of radiation, it won't work, without adding or subtracting one type or another.

If however, you are working with all BB or all CI radiation, the curve on your reset can be tailored to match the emitter you have. This allows you to run the system at condensing temps for at least a good portion of the heating season if not most of it.

Floyd_7

No extra air....

there is no way that extra air can be run into this pupppy at high temps. I have noticed though that at higher temps. the flue temps. seem to flatten out and stay well below return temps. I think inmay have something to do with the lip of the HX that sticks out and holds the S/S flue pipe starter. The outdoor air is brought in washing over this S/S section which I wold think transfers a ton of the heat to the intake air and also cools the flue down considerably. I would wonder how in would perform if the cover was left off of the boiler in a high ambient situation and the heat transfer couldn't take place. I have a place that I can experiment.... I may be able to do that soon.....

I'll get back to you's......

Floyd

.

> however, you are working with all BB or all CI

> radiation, the curve on your reset can be

> tailored to match the emitter you have. This


Not with my Munchkin's Vision I. Straight lines only. A real pain. I wish I had understood, before getting the Munchkin, what a bad design this is.

Dave_49

Attention Reynz

Reynz I have a similar set-up to yours, and would love to talk to you about how yours is set up. I want to make sure I am getting top efficiency from my system. Please contact me.
Thanks
Dave

Reynz_2

No Problem

I've emailed you with my phone number. Feel free to call....

Reynz

Kal Row

i left the question on the WM site with this link..

lets see if they bite

Kal Row

question for you

floyd, have you ever put two plus’s in series, and have the boiler’s indirect loop in series also, so that boiler’s return comes from the coldest point, sure, the boiler cant put out more btu's than rated, and wont cook two pluses any faster, however with the extra plus, with it's aquastat disconnected, over time the cold street water will get preheated, and the boiler will get cooler return water where it can fully utilize condensing – and once the primary plus’s aquastat set at 160 cuts off, the secondary plus will be sitting at 80-100 – once in this state, I should have standby capacity – easily equal to 100gal gas standard water heater – so in this app I can get away with an ultra105 – cause if I sized it for full instant host water demand – I would need a 155 – so I am exchanging time/space for capacity, and this way – I first put in a 105 and one plus, if then there is not enough hot water, I just add the seconds plus – without changing loosing anything, wod-ya-tink??

Floyd_7

never did that...

but in theory it should work.....my concern would be the cost of the two plus's... I do have a uninsulated range tank before my plus 40 in my house so that the well water is tempered a bit before it hits the indirect. I also have my 155 tamed down to a max of 140* output for the indirect and it still heats 120* water just fine... never run out.... I do have the boiler enabled to run to the full 155 for the indirect. For the space heating I have the fan speed limited to 3500, that way I never have the boiler running at full fire for space heating, I don't ever need it.
I emld WM today and they just gave me a sond and dance about how the boiler HX is so eff. and the water is counterflow, therefore the low flue temps.......don't think they want to give too much away there.......the boiler will mod. down if the supply and return sensors feed back that the boiler is putting out more BTU's than the water is taking away, however. Also it will mod. down if the flue temps. get too high. I will do some playin' if I get time, or the chance.
I also asked them about bending the reset curve... they said not yet, but that they may have a switch coming in the near future that will shift the curve if more heat is needed temp. (ie. if the power goes out and you need to catch the space back up).
Let's keep talking to them, the more positive feed back they get from us, the more incentive for them to keep ahead of us and make positive changes in their product.
These boilers seem to be tremedously durable and pretty much idiot proof.....mine in my house is NOT even hooked up P/S!!! did it that way just to see if it would work, and it does just fine.....I am going to change to a 0013 pump instead of the 0011 soon, just to see what it will do with that, I think I can get enough flow then to get it running just like a P/S would with 0011.......my system is a 1-1/4 main line with monoflow tee's so the restriction is less than many systems out there.....
Enough rambling, it's bedtime!!

Floyd

Kal Row

ok have the answers from WM

> but in theory it should work.....my concern would

> be the cost of the two plus's... I do have a

> uninsulated range tank before my plus 40 in my

> house so that the well water is tempered a bit

> before it hits the indirect. I also have my 155

> tamed down to a max of 140* output for the

> indirect and it still heats 120* water just

> fine... never run out.... I do have the boiler

> enabled to run to the full 155 for the indirect.

> For the space heating I have the fan speed

> limited to 3500, that way I never have the boiler

> running at full fire for space heating, I don't

> ever need it. I emld WM today and they just gave

> me a sond and dance about how the boiler HX is so

> eff. and the water is counterflow, therefore the

> low flue temps.......don't think they want to

> give too much away there.......the boiler will

> mod. down if the supply and return sensors feed

> back that the boiler is putting out more BTU's

> than the water is taking away, however. Also it

> will mod. down if the flue temps. get too high. I

> will do some playin' if I get time, or the

> chance. I also asked them about bending the

> reset curve... they said not yet, but that they

> may have a switch coming in the near future that

> will shift the curve if more heat is needed temp.

> (ie. if the power goes out and you need to catch

> the space back up). Let's keep talking to them,

> the more positive feed back they get from us, the

> more incentive for them to keep ahead of us and

> make positive changes in their product. These

> boilers seem to be tremedously durable and pretty

> much idiot proof.....mine in my house is NOT even

> hooked up P/S!!! did it that way just to see if

> it would work, and it does just fine.....I am

> going to change to a 0013 pump instead of the

> 0011 soon, just to see what it will do with that,

> I think I can get enough flow then to get it

> running just like a P/S would with 0011.......my

> system is a 1-1/4 main line with monoflow tee's

> so the restriction is less than many systems out

> there..... Enough rambling, it's

> bedtime!!

>

> Floyd

Kal Row

ok people - WM got back to me...

#1)how come, the flue is 158 max if the return water is lets say 170?
because of latent heat of condensation - even though, we are not fully condensing, we are still condensing – and when something condenses – if gives up the heat that kept it vaporized, eg the discharge from a compressor is to hot to touch, but after one turn through the condenser it can be touched even though it’s still mostly vapor at that point, so: even 190 water coming back to the ULTRA will condense the flue gas somewhat, and EXTRACT enough heat from the flue gas to cool it down to 158 – btu transfer via state change - we were thinking temperatures not state change – duh

2) given a house with a heat loss of 85 – but a huge hot water need – is it better to get one indirect PLUS tank and an ultra 155, or, one ultra 105, and 2 indirect PLUS tanks in series?
– WM’s answer: if you have some time between huge hot water demands, then two indirects in series is way way way cheaper to run and highly recommended –

ps their indirects can be run to 200 – so running it up, and putting an output tempering valve to add capacity IS recommended

Kal Row

i feel sooooo stuuuupid... all this time i knew...

that combustion produces co2 and h20, so if any part of an HX is below 212 - the H2O will condense on it and give up it's heat - duh!!!
Running state, CasrIron boilers run the flue so hot that the h2o is vapor all the way to the top – what a huge waste of perfectly good energy