Short Run Time for Circulators

bighouse
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Post Fri. Oct. 24, 2008 7:47 pm

Hi, I have a 2 -zone hot water system with the EFM 520. My question is..Is it normal for the circulator pumps to run only about 30 sec. at a time when the thermostat calls for heat. Then pumps shut off ( for about 1 1/2 min.) until boiler temp. goes back up. The radiator in my daughters room never gets the hot water cause it is last in line and by that time the thermostat is satisfied. How do I get water to continuosly circulate until boiler reaches set limit? I know I don't have a bypass. Could I set lower limit really low so that pumps run longer? I have the domestic water going into hot water heater (gas for backup), then to the house so boiler water temp. could be low and that would'nt hurt my Domestic water. I don't know what to do, but I am tired of hearing my daughter complain about her room being so cold and my wife and I have a nice toasty room (wife's happy!). Thanks for any help.

Mark

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rocketjeremy
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Post Fri. Oct. 24, 2008 7:59 pm

Bighouse.....I'm by far no expert....but what are your settings....hi/low and your differential?

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Freddy
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Post Fri. Oct. 24, 2008 8:15 pm

Hmmmm... my brain might be on backwards tonight, but, some boilers won't run the circulator if the boiler water temp is too low. The idea behind that is it allows the boiler to always have heat for domestic hot water. So, I'm thinking when the circulator comes on it draws the heat down, the pump shuts off. In my mind the answer would be to RAISE the low temp, not lower it. Then you'll have more BTUs sitting in the boiler waiting to go. Also, depending on how the pipes are plumbed, you might partially close all the other valves and leave the one in your daughters room full open. That will drive more heat out there. If they are all in series, that won't work.

At one point you say "by that time the thermostat is satisfied". It's possible that there is simply too much radiation on that zone and the only real cure is to run new pipes to your daughters room.

bighouse
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Post Fri. Oct. 24, 2008 8:22 pm

rocket jeremy, my settings are 190 high, 160 low with 10 diff.

Bob
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Post Fri. Oct. 24, 2008 9:14 pm

Check the anticipation setting on your thermostat. A high anticipator setting can lead to short cycles. Better yet put in an electonic thermostat if you are still using an older style thermostat.

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stoker-man
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Post Fri. Oct. 24, 2008 10:24 pm

Try the differential at 25, the low limit at 140, and of course, you need a bypass line. A Taco 008 will also help by moving a large amount of water at a slow speed.

Mark (PA)
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Post Sat. Oct. 25, 2008 9:38 am

How are your Zones hooked up? relays? It sounds very strange for them to shut off in 30 seconds. Just wondered if there was something amiss in the setup?

Placement of the thermostat always plays a roll in that. you can move the thermostat to your daughters room. thus the other rooms may get too hot!?! but in any case maybe moving your thermostat will help. but none the less moving that thermostat or leaving it there shouldn't have anything to do with it turing off in 30 seconds. also as mentioned maybethe anticipation on the thermostat is off?

is it a new install or has it always been like this?

setting your lower limit really low wouldn't have anything to do with it but if you move your upper limit down some you therotically would have your circulators run longer as it would take longer to heat your space but it should be a move even heat.

let us know!

bighouse
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Post Fri. Oct. 31, 2008 8:53 pm

Thank you all for your help. Stoker-man hit it on the nose. There is no by-pass. I asked my plumber to install a bypass and what he did was to put in a equalization loop.. I'm new at this so when I told him I wanted a bypass put in, he put in the equalizing loop ( which I thought was a bypass). After reading your help, I told him that an equalizing loop is not the bypass I needed. He seemed mad and wanted to know who I was talking to. I told him it was in the diagram in the EFM 520 manual. I can't get a good plumber so save my life. From now on, I am going to do it myself ( slowly, of course and hopefully with help from this awesome forum. Thanks again for all your help. I'm now going to look in the forum to find out how to set my draft correctly because I am burning a lot of coal compared to last year and it's not even cold yet. I think this plumber really screwed me up.

Mark

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stoker-man
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Post Sat. Nov. 01, 2008 6:25 am

What did the plumber do to make the equalizing loop? I'm not clear about what he did.

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Freddy
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Post Sat. Nov. 01, 2008 7:04 am

Did the equalization loop (never heard the term) cure the problem?

bighouse
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Post Sun. Nov. 02, 2008 10:34 am

Stoker-man, the plumber put a copper pipe from bottom left boiler to top of boiler output. He said it will mix the cooler and warmer furnace water????? When I asked him about a bypass line, he became defensive and wanted to know who I was talking to. I told him it is in the EFM manual. He just defended his equalizing loop. I will try to attach a picture of my system and the loop he put in.
furnace2.jpg

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stoker-man
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Post Sun. Nov. 02, 2008 1:29 pm

Your return line should go to both bottom returns and valves should be used to force some of that return back into the feed, as shown in the efm manual.

IceDog
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Post Tue. Nov. 18, 2008 4:50 pm

Stoker-man,

What is the reason the return line should go to both bottom returns? I see it's that way in the EFM manual.

I just looked at my boiler and the plumber only ran the return to the bottom left (looking at it from the back). He has a "bypass" line from the output of the boiler down to where this return goes in.

I'm asking because I have 1 1/4" piping that goes into cast iron base board on my first floor and 1" piping that goes to the cast iron baseboard on the 2nd floor. I think I'm "shocking" the boiler. I see the boiler temps get down as low as 100 degrees now that the heat is running.

I noticed that my stoker does not kick on when the circulator starts, and the circulator keeps running until the thermostat is satisfied. Needless to say forget about getting domestic hot water if the boiler is only at 100 degrees.

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cArNaGe
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Post Tue. Nov. 18, 2008 6:06 pm

Icedog

Open your bypass if your return water is that much.

What aquastat are you running to control your boiler temp?

How many circulators do you have?

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stoker-man
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Post Tue. Nov. 18, 2008 6:10 pm

There is 41 gallons of water in your boiler, so returning to one side only will create zones of varying temps inside the boiler. The bypass loop will help prevent stratification of the water, but if you adjust the valves properly, you should force alot of the return water back into the supply loop. This not only provides more temperate water to the radiators, it also doesn't allow the boiler to be shocked as much by the cold return water.

If your triple aquastat is working properly (set it at 10-15 differential for cast iron), your circulator should stop when the boiler water drops below the low limit setting. The triple has a reverse acting function to "open" on temperature drop, thus shutting off the circulator. Is your aquastat's probe properly inserted into its well? Are your settings 160/200? Are you keeping the house at a constant temperature or setting it way back at night? Usually 5 degrees setback is about as much as you should go.

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