Boiler tempurature drop

Boiler tempurature drop

PostBy: papcun52 On: Sun Oct 19, 2008 12:13 pm

I have a new efm 520, and a honeywell L7224 (or something close to those numbers) aquistat. I set the differential on 25 degrees, low temp is set at 160. My pump only runs for about 4 minutes before the boiler tempurature drops to 135 and shuts it off. Then it takes about 8 minutes to recover back up to 160. This doesn't seem very efficient. I feel that the pump should stay on longer to pump water to all the radiators. I had the stoker set at 3 - 3.25, but I just jacked it up to 7-6 because my furnace ran for 5 hours this morning and my house wasn't heating up.
I don't have a large house, it's an old 2 story with about 1600 square feet of living space. I only have 9 radiators. The variable in this whole thing is my plumbing, for some reason there are 2 inch steel pipes in my basement, they are used for the main lines for the hot and return lines. I think they fill up with a lot of water then the pump shuts off and I have a lot of hot water sitting in those big pipes.
Any input would be great. Should I have a bigger pump? A better fire?
papcun52
 
Stove/Furnace Make: efm
Stove/Furnace Model: 520 boiler

Re: Boiler tempurature drop

PostBy: billw On: Sun Oct 19, 2008 12:55 pm

Are your pipes insulated? 2" pipe makes for one big unintended radiator. BTDT All that cold water in those pipes is getting dumped in the boiler and cooling it down quick. Wait and see what your feed rate change does.
billw
 
Stove/Furnace Make: EFM 520
Stove/Furnace Model: GOODBYE OIL COMPANY

Re: Boiler tempurature drop

PostBy: Freddy On: Sun Oct 19, 2008 2:07 pm

Does the boiler have a bypass valve? I think the cold load is dumping the boiler temp and causing short cycling. A bypass valve would help keep the boiler temp more constant.
Freddy
 
Stoker Coal Boiler: Axeman Anderson 130 (pea)
Hot Air Coal Stoker Stove: Reading piece o' junk in the barn (rice)
Coal Size/Type: Pea size, Superior, deep mined

Re: Boiler tempurature drop

PostBy: cArNaGe On: Sun Oct 19, 2008 2:31 pm

I agree with Freddy. If you have a bypass valve open that up some.
cArNaGe
 

Re: Boiler tempurature drop

PostBy: mozz On: Sun Oct 19, 2008 2:37 pm

Is this steam heat or hotwater baseboard?
mozz
 
Stoker Coal Boiler: Axeman Anderson 1982 AA-130 Steam

replies

PostBy: papcun52 On: Sun Oct 19, 2008 4:08 pm

The large pipes are not insulated. I will probably do that before the real cold weather comes.

When my father in-law and I installed the boiler we didn't see the need for a bypass valve...now I know what it would do for me. He didn't have one on his boiler so we wrote it off as something that wasn't necessary. But he has soft coal hand fed boiler. Anyway, I don't have one, I'll consider putting one in next year.

This is a hot water, radiator system.

Thanks for all your replies so far.
papcun52
 
Stove/Furnace Make: efm
Stove/Furnace Model: 520 boiler

Re: Boiler tempurature drop

PostBy: jpen1 On: Sun Oct 19, 2008 4:27 pm

What you have is a very poorly done coonversion from steam to hotwater . Those 2" pipes in the basement are pulling all the hotwater out of the boiler and filling it with the cold water of your radiators but since the pump is running such a short amount of time the radiators aren't even seeing the temp of water desired. I think you are going to use double the fuel normally needed to heat a house that size with out the bypass valve and way oversized supply piping.
jpen1
 
Stove/Furnace Make: Leisure Line
Stove/Furnace Model: 110 Boiler

Re: Boiler tempurature drop

PostBy: mozz On: Sun Oct 19, 2008 5:56 pm

When he said 2" pipe, it rang a bell. I just installed a AA130 with steam and know all about 2" and 1 1/4" pipes too well. Do they run a 2" circulator pump for that? There has to be a real lot of water in that system.
mozz
 
Stoker Coal Boiler: Axeman Anderson 1982 AA-130 Steam

Re: Boiler tempurature drop

PostBy: coalkirk On: Sun Oct 19, 2008 6:46 pm

I doubt it was a steam system unless he changed the radiators. Older hot water systems were gravity circulated and needed the larger pipes. I don't know how much water your boiler holds but those 2" pipes hold alot. Insulating should help some. I'd lower the differential so that your boiler fires earlier also.
coalkirk
 
Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

Re: Boiler tempurature drop

PostBy: stoker-man On: Sun Oct 19, 2008 7:36 pm

Time for a bypass valve.
stoker-man
 
Hand Fed Coal Boiler: 1981 efm wcb-24 in use 365 days a year
Coal Size/Type: Anthracite/Chestnut
Other Heating: Hearthstone wood stove

bypass valve huh?

PostBy: papcun52 On: Sun Oct 19, 2008 7:54 pm

I have an idea...maybe I should install a bypass valve :) I will probably need to drain my system though, because I don't have room on the other side of my return shut off. I hope this works...
Thanks for all the advice. I'll probably get to it next Saturday and let you know if it is working better. Thanks again.
papcun52
 
Stove/Furnace Make: efm
Stove/Furnace Model: 520 boiler

Re: Boiler tempurature drop

PostBy: jpen1 On: Mon Oct 20, 2008 8:11 pm

Terry If it was an old 2 pipe steam sytem all you would have had to do was remove the steam traps and add a circulator to the boiler's out side, an expansiontank/filltrol and balancing valves to each radiator. The only problem with doing this is the inefficiency factor. 1" copper pipe holds roughly .04 gals per linear foot however 2" copper would hold something like .16 gals per linear foot of pipe if my math is correct .
jpen1
 
Stove/Furnace Make: Leisure Line
Stove/Furnace Model: 110 Boiler