Boiler/water heater shtick--Bill Clinton

Bill Clinton

Come on guys, pile on, tell me I'm wrong. It's Sunday evening and I just faxed a proposal to a condo committee head proposing to tear out the Laars boilers they have installed in individual condos and install water heaters instead! I wrestled with this for days, but my conclusion was that this was the best way to handle the situation.

The situation: There are 16 condo units. Most of them are two story: slab first floor, joisted second floor with carpets.

The contractor who installed this system used oversized Laars boilers with 1/2 non-barrier pex in the slab, and same stapled up between the joists, two passes per bay (8" centers). He used the same temperature for both zones. Expansion tank is steel; air remover is cast iron, circulator is cast iron. The following problems are observed:
1. Inadequate heat upstairs
2. Too much heat downstairs (overshoot).
3. frequent boiler cycling
4. rusty water
The following problems are anticipated:
5. Sooting up and corrosion of boiler because of
condensing on cold starts
6. Corrosion of circulators
7. Dead boilers when circulator fails because there is no
flow switch protection

There's a pretty sharp guy there who has retrofitted some of them with a buffer tank and set them up primary/secondary with two zone pumps and a mixing valve for the lower story. He intends to put in a corrosion inhibitor--Silver King, I believe. All that's needed now on these units is flow switch and low protection against low temperature return water. This guy is probably reading this post right now.

They asked me to upgrade the remaining units. I don' wanna.
To my mind they wind up with a Rube Goldberg complex system that few service people could figure out, and fuel efficiency would still be only sorta ok.

On the other hand, If I install a dedicated water heater and replace the iron/steel parts as needed, no need for water treatment, no need for flow protection, no worry about return temperature. Plus, a halfway competent service person could trouble shoot it in his sleep. My take is the fuel efficiency might be a little less than the Laars, but not a bad trade-off.

Contrary to my reputation, I install a lot of boilers and, if I were to be doing this job from scratch and had control of the way it was installed, I would have used cast-iron boilers and piped it up very differently. As it is, I think my proposal is a better system. It also is considerably less money than the retrofit. What say ye.

Bill

Steve Ebels

I'd suggest

> Come on guys, pile on, tell me I'm wrong. It's

> Sunday evening and I just faxed a proposal to a

> condo committee head proposing to tear out the

> Laars boilers they have installed in individual

> condos and install water heaters instead! I

> wrestled with this for days, but my conclusion

> was that this was the best way to handle the

> situation.

>

> The situation: There are 16 condo

> units. Most of them are two story: slab first

> floor, joisted second floor with carpets.

>

> The

> contractor who installed this system used

> oversized Laars boilers with 1/2 non-barrier pex

> in the slab, and same stapled up between the

> joists, two passes per bay (8" centers). He used

> the same temperature for both zones. Expansion

> tank is steel; air remover is cast iron,

> circulator is cast iron. The following problems

> are observed: 1. Inadequate heat upstairs 2.

> Too much heat downstairs (overshoot). 3.

> frequent boiler cycling 4. rusty water The

> following problems are anticipated: 5. Sooting

> up and corrosion of boiler because of

> condensing on cold starts 6. Corrosion of

> circulators 7. Dead boilers when circulator

> fails because there is no flow switch

> protection

>

> There's a pretty sharp guy there

> who has retrofitted some of them with a buffer

> tank and set them up primary/secondary with two

> zone pumps and a mixing valve for the lower

> story. He intends to put in a corrosion

> inhibitor--Silver King, I believe. All that's

> needed now on these units is flow switch and low

> protection against low temperature return water.

> This guy is probably reading this post right

> now.

>

> They asked me to upgrade the remaining

> units. I don' wanna. To my mind they wind up

> with a Rube Goldberg complex system that few

> service people could figure out, and fuel

> efficiency would still be only sorta ok.

>

> On

> the other hand, If I install a dedicated water

> heater and replace the iron/steel parts as

> needed, no need for water treatment, no need for

> flow protection, no worry about return

> temperature. Plus, a halfway competent service

> person could trouble shoot it in his sleep. My

> take is the fuel efficiency might be a little

> less than the Laars, but not a bad

> trade-off.

>

> Contrary to my reputation, I

> install a lot of boilers and, if I were to be

> doing this job from scratch and had control of

> the way it was installed, I would have used

> cast-iron boilers and piped it up very

> differently. As it is, I think my proposal is a

> better system. It also is considerably less

> money than the retrofit. What say ye.

>

> Bill



Boilers yet. Use a flat plate or whatever type stainless steel HX you choose to isolate them from the non-barrier side of the system. Use a mixing valve to get your two different temps. Use a boiler capable of handling low temps (I don't know what the load is so can't recommend a specific one) Buderus or Viessmann come to mind. Presto good efficiency and low maint. JMHO

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Duncan_2

Nay, I say

Fix it so it addresses the concerns and stays fixed, or walk away. As you describe it, the only problem you're addressing is the short cycling and (as yet non-existent?) anticipated sooting. Your fix addresses those concerns simply and effectively. But not the other concerns you listed, so in that respect, you're wrong (hey, you said to tell you you're wrong!).

I agree that sooting could become a problem with an oversized non-condensing copper fin tube boiler, but for different reasons. Short cycling will corrode the vent and heat exchanger and eventually clog it. Ive seen it before on systems where heat is produced quickly, but delivered slowly. Conversely (or is that perversely?), I've seen copper fin tubes that look fine after years of being directly connected to radiant slabs.

Soot and circ corrosion hasn't happened yet, but there's a bid to replace the system? Lemmee guess... The system's only been in two years and the REAL reason for bid is that someone's getting screamed at for huge fuel bills and no heat upstairs. Don't let that someone become you, Bill. Address the other concerns or bail.

Flow switches are required for commercial installations in most areas, are condos a different animal? Don't have many of those here in Teller County.

P.S. When you say water heater, what kind do you mean?

Joel_3

condo

My first concern would be the No heat upstairs thing, How is any heating plant change going to fix that? if there aren't plates up there or adequate insalation i really don't see how it would be much better. Your post seemed to imply the firstfloor overheated. Potentialy from heat coming down from above?? How high are the bills? Be careful condos are notorious for shoddy construction, thier bills could be due to poor sealing and insulating. If you replace everything and it was communicated to tenants, even hinted at, that comfort would go way up and bills would go down you may find yourself in a world of hurt!! Not having seen it I'd probably consider adding a flat plate HX to protect the boiler. If your talking a standard WH it will fail in what 5-10 years?? Who knows? those peole will forget all about the cheap up front cost. We take care of a condo complex with heat pumps that are very uncomfortable and very exspensive to run they are 10-15 years old and dropping like flys. The people blame us!!!!! and we didn't put them in!! "Well you've serviced it for years, why did it fail? what am I paying you for Blah blah blah" Unreal the abuse we take in this industry!! Think they'd go back to thier car mechanic after 15 years and say "What do you mean it's junk!! you changed the oil and did the brakes for 15 years!! What was I paying you for? Some of them want us to actually GIVE them a new heat pump for free!! (They did offer to pay for labor)imagine going to the dealer and asking them for a new car!

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Boilerpro

Haven't seen this in person yet,

but a water heater in a rad slab system can and apparently does condense....sometimes severely. Ran into a nonprofessional who did his own installation for a radiant slab in his shop. Apparently once a year he has to pull out the flue baffes because it gets completely clogged with rust and soot... it maybe chemicals in the shop I suppose, but I bet the water heater is running too cold.

Boilerpro

hr

What about DHW

how is that handled? Did you crunch the numbers to see what temperature the upper level needs? What about insulation in the celing?

The buffer tank on the current boilers may not be a bad fix. You could offer DHW with an indirect as the buffer. Sounds like a "can O worms", haed to make a call without seeing more

hot rod

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don_9

Right on

Joel,We can do the best job with the best equipment going today,But if the frame is poorly constucted we have no chance in hell at controlling the quantity or quality of
ones comfort.Run Bill, run !

Bill Clinton

thanks Duncan

I can address all the concerns with a water heater. The upstairs heat can be made marginally ok by running 160 degree water. It doesn't get that now because the boilers are turned down to accommodate the slab, and because the boilers have a 30 degree delta tee aquastat. Still; too warm for the slab, too cool for the upstairs.

I too have seen many copper boilers working fine on slab radiant and used to install many Laars boilers with no protection against condensation. All was fine 'til they improved the efficiency a couple of points. Now they soot up easily.

Around here, flow switches are not required on residential. Every copper boiler should have them though.

The water heater I would be using would be a tank type with 80% combustion efficiency, and yes, I would have to install an aquastat to shut off radiant circ if temp drops--to prevent condensation.
Bill

Bill Clinton

Dhw is separate.

Didn't need to crunch the numbers to see what the upper level needs for water temperature: The guy who has retrofitted some of the units with buffer tank, etc, has managed to control at 160--170 degrees and the upstairs is then ok; my impression is a little more wouldn't hurt but I'm not a fan of running pex above 160 for long periods.

Yes, there is insulation in the ceiling. Overheating downstairs seems to be a matter of overshoot due to high water temp.

Bill

PJO

It may be whacky at first thought, but...

what if you put an Ergomax type of tank on each unit. You would get your heat exchanger and buffer tank, and you could set the temp for the downstairs (off the "feed side" of the Ergo) while running the upstairs at full temperature. It would entail more pipe work and another circulator, but would this not solve many of the problems here?

I have posted this question before about using it for a situation like this, but never got a response. Any thoughts on this, folks?

Take care, PJO

Bill Clinton

interesting idea

I'll have to give it some thought. The only objection I've had to Ergomax is that when pumping out of the tank, I either have two circulators fighting each other or I have unwanted circulation through the boiler during off cycle. Wish they would put in a couple of extra tappings. Still, gotta consider it.
Thanks

Bill

Bill Clinton

interesting idea

I'll have to give it some thought. The only objection I've had to Ergomax is that when pumping out of the tank, I either have two circulators fighting each other or I have unwanted circulation through the boiler during off cycle. Wish they would put in a couple of extra tappings. Still, gotta consider it.
Thanks

Bill

Art Pittaway_2

It's necessary to

put 30# relief valves in those heaters with backflows & PRV's. Hey, BoilerPro, I keep hearing about these water heaters that are rotting out from condensation but I have yet to see one.??? What's "medium" on a waterheater, 100 - 110F? If your going to need 160F to heat the upstairs, your at the top of the control dial. That would stop me from going with a waterheater. Also, did you do a heatloss on the upper and lower floors? Installed properly, I've seen water heaters work great. My 2 cents.

Andy N.

condensing in water heaters.....

I have experienced this first hand. I installed several water heaters for radiant slab applications and I know that one of them needs to have the burner removed annually for cleaning. the rust piles up on top so bad it interferes with the operation. this is an A.O. Smith Powervent heater, and I had it set at 115. I followed hot rods advice and cranked the temp. up about to about 125 and am looking forward to seeing how bad it is this year. I am also planning on removing the heater and installing a boiler this fall.