Water Temperature

Stoker Coal Boilers automatically feed the coal and have controls and pumps just like any conventions boiler. They are intended to be used as a primary heat and often have domestic hot water coils as an added bonus. They can be set up independently or in dual sytem with your existing oil/gas boiler. They can accommodate both hot water base board or steam plumbing.
bighouse
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Post Sun. Feb. 24, 2008 11:05 am

Hi, I have an EFM 520. My house is a large 3story brick with about 20 cast iron radiators and 2 zones. (1st floor=zone 1) ( 2nd , 3rd. floor=zone 2). My question is can the water temperature in the boiler fall to about 90* when the thermostats call for heat? I have a brand new triple aquastat set at high 180, low 160 w/ 10 diff. I cannot use the domestic coil cause if the house calls for heat the water is lukewarm from the coil ( it is a new coil). I have the furnace set at 4 teeth and 4 1/2 air. Is it too low? Also, water pressure is about 10-12 lbs. Should I add water cause there is not much pressure on 3rd floor when I bleed radiators? I really like the furnace better than the old gas one we had but I just want to have it as effient as possible. I went through 14 ton last year and friends said that was probalby doulble what I should have gone through. We ended up probably paying same amount as with gas but we were warmer.

Thanks for any help.

Mark

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Richard S.
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Post Sun. Feb. 24, 2008 11:23 am

The drop in temp is quite a bit but on the other hand 20 cast iron radiators are going to hold quite a large volume of water.

The first thing that needs to be addressed is how big is your house, how many sq feet of living space are you heating? Also is it well insulated? New windows? These are all big factors in the amount of coal you will use. Putting in new windows for example will drastically cut the maount of coal you use, I could actually guess when customers did this as their usage would generally drop about 1/3.
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gaw
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Post Sun. Feb. 24, 2008 11:36 am

Was the boiler installed with a bypass loop? You may need to up the feed it sounds like a large house.

A rule of thumb I was told was to use 12 psi for baseboard heat and 15 psi for cast radiator. Also heard to increase pressure to 15 psi for baseboard if over 2 stories. Low pressure is not the reason your domestic water is too cool.
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e.alleg
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Post Sun. Feb. 24, 2008 1:07 pm

The reason the domestic hot water is cold is because all the heat is being radiated by the radiators. You can turn up the feed/air to solve this problem, or turn off some of the radiators. You might be able to get by comfortably with 10 radiators and shut the other ones off, or maybe throttle them down depending on how they are plumbed together. You might need a larger bypass loop or adjust the balancing valves so more boiler water is being recirculated back into the boiler instead of going to the radiators, but then you might cause other problems.

I would seal off as many drafts as possible and lay down some 12-24" thick insulation in the attic floor, I have a large Victorian and insulating the attic made a huge difference. We only use it for storage so I closed it off and insulated the heck out of it, now the roof has snow on it all winter.
Burning coal is definitely worth the extra work involved.
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stoker-man
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Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove
Location: Lehigh Valley, PA

Post Sun. Feb. 24, 2008 2:29 pm

Your triple aquastat is supposed to turn off the circulator when the boiler water temperature hits 150 ( your settings are 160-180). Also, with cast iron radiators, you should have the low limit set at 150 with a 15 degree differential.

Your pressure should be closer to 15# and I don't know how you can do it with 4 teeth feed of coal. Maybe you can.

You should have a bypass loop installed which diverts about half of your return water right back out into the supply loop.

Is this low water temperature happening after a night at a setback temperature? If so, you might have a low boiler temperature because without a bypass loop, it is being flooded with 60 degree water. Once the house is warmed up, does the problem resolve?

Do you have a draft regulator installed and properly adjusted for a reading of neg. .02 over the fire? This is a more important reading than the draft at the breech. However, the two are usually proportionate to each other.
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bighouse
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Post Sun. Feb. 24, 2008 6:30 pm

Thank you all so much for the answers. I do know that there is no bypass. That then makes sense for the 60* water flooding back into furnace. It is not just after night that it happens. It happens during the day also (temp. will go down to about 90*) I think it is just the amount of water volume. I will see about correcting for a bypass this summer. I will also adjust my aquastat settings accordingly and up the feed and air as stoker-man suggest. I will also shut off or partially close radiators in 3rd. floor as it is rarely used (holidays, etc.). I got new windows for the downstairs this year and hope to get more for rest of house in the next couple of years.

Does it matter that I have programmable thermostats or should I just keep house set at a comfortable 70* at all times? Also, I do have a draft regulator installed but am unsure how to set it. Guy who installed set it and did not tell me how it works. it is a type R-C calibrated draft contol. how do you measure draft. Sorry for the beginner questions. You guys are great asset.

Thanks,
Mark

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stoker-man
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Location: Lehigh Valley, PA

Post Sun. Feb. 24, 2008 8:18 pm

There is a manometer loaner program on this forum, to adjust the damper, but I don't know who is in charge of it. Depending upon your climate, the setback at night can be so far back that you really don't benefit in fuel savings. In this area of PA, the HVAC guys limit it to about 5 degrees.

The efm manual shows the bypass loop installation. Was this unit in your house when you bought it? or is it new and the installer forgot to install it?
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bighouse
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Post Sun. Feb. 24, 2008 9:14 pm

Thanks stoker-man. By the way, I live near Altoona, PA. I bought the unit used and had a plumber who had installed a few others put it in. He put in in for a reasonable price but did not really tell me much about it. He used the existing piping from the gas furnace that the EFM replaced, and I really don't think that there is a bypass. I think he just wanted to get in and get out. Tomorrow I will try take take a picture of the setup and post it. The guy I buy coal from gave me the manual. I will try to figure out volume of water in radiators. How do I then figure out feed teeth when I know water volume or should I just figure out square feet of living space? Also, radiators sometimes make a loud noise, usually at night when thermostat goes to lower setting. Is that noise just the water cooling in the pipes? I bled all the radiators until I got water, but there are some pipes in basement where old gas furnace was that looks like a rats nest. Could air be trapped in that rats nest of pipes and not be able to escape through normal bleeding of radiators?

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stoker-man
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Location: Lehigh Valley, PA

Post Mon. Feb. 25, 2008 5:46 am

Air could be trapped, but usually all air goes up, eventually.

Are you using multiple circulators or one with zone valves?

With the boiler water at 150, you should have less noise at the radiators and with Taco 007s, you'll have slower water flow than with a B&G 100. The cast iron movement and pipes rubbing against wood make the noise when they expand and contract.

There is a thread in this area about how to determine the BTU ratings of your rads. A Manual J calculation will then tell you how many BTUS you need to heat the house. Or you can just increase the coal feed/air and fly by the seat of your pants.
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oilman
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Post Mon. Feb. 25, 2008 6:11 pm

Your zones are not wired using z/c and z/r off the aquastat. You have no circulator reverse.
You really need to have the boiler piped properly. 90 degree return water will destroy the boiler. Can't do it.
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QUESTMAN
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Post Mon. Feb. 25, 2008 8:05 pm

Sounds like your expirencing "thermal Shock" to the boiler--Install a bypass line from the feed back into the return line with a ball valve in line to temper the water returning to the boiler. Constatnt low water temperature will destroy your boiler.

bighouse
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Post Mon. Feb. 25, 2008 9:55 pm

Hi guys, I am using (2) Taco 007 circulators for the 2 zones. Oilman, On the aquastat only the z/r has a black wire to it, no wire to the z/c. Stoker-man, 4 teeth has kept house comfortable but then again it has been in the low to mid 30's. I will increase teeth (fly by seat of my pants) when in 20's. The plumber who put my EFM in also did a few others for people and I wonder if they are having problems also. I'll never use him for anything again. There is a plumber in Bedford county, PA that my coal guy says is good. If I get him to plumb this right should I get the circulators put on the supply side instead of the return and then also put in a bypass valve. I can't thank you guys enough for your help. I have to avoid destroying the boiler with the low return water temp. I did not even know that could happen.
Thanks
Mark

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stoker-man
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Location: Lehigh Valley, PA

Post Tue. Feb. 26, 2008 5:47 am

Hi guys, I am using (2) Taco 007 circulators for the 2 zones. Oilman, On the aquastat only the z/r has a black wire to it, no wire to the z/c.

That's the wire from the timer.

Stoker-man, 4 teeth has kept house comfortable but then again it has been in the low to mid 30's. I will increase teeth (fly by seat of my pants) when in 20's.

If it heats on 4 teeth, let it stay there, but you'll have a slower recovery rate for your domestic coil when the cold return water hits the boiler, until you get your bypass piping installed.

The plumber who put my EFM in also did a few others for people and I wonder if they are having problems also. I'll never use him for anything again.

You don't have to be too hard on the guy. If you had copper baseboard and a smaller house, maybe you wouldn't have needed the bypass line.

There is a plumber in Bedford county, PA that my coal guy says is good. If I get him to plumb this right should I get the circulators put on the supply side instead of the return

Supply side pumps seem to eliminate air better than return side. Just use shut-off flange valves on either side of the circ. for possible future replacement.
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bighouse
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Post Tue. Feb. 26, 2008 10:46 am

Stoker-man, thanks again for your help and thanks to all who responded to my questions. You all have been very helpful and informative. After I get things straightened out this summer I will post the results of your recommendations.

Thanks,

Mark

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e.alleg
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Post Tue. Feb. 26, 2008 1:40 pm

If I get him to plumb this right should I get the circulators put on the supply side instead of the return
do a search, we debated about this a little while back. in summary: some experts think "pumping away" is best, others think the old way is best. Most agree that a circulator just circulates water so it doesn't matter where the thing is. The benefits of pumping away are all positive and have to do with air extraction, noise reduction, pressure fluctuations, with a possible reduction in pump life being the only downside.
Burning coal is definitely worth the extra work involved.
"Good enough" is not good enough.

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