# Circulator pump only runs when house calls for heat



## pipe76 (Sep 17, 2008)

Hi folks, 

Just wanted to get people opinion on a trail setup I have. - I have a 
new Central Boiler, 6048. 130' ft from the house. My pump is located 
inside the house, with no problems. First hooked it up about 20 days 
ago, and ran it just to make sure everything worked ok before it gets 
cold. Ran it for about 15 days just for hot water, with the pumps 
running all the time like the manual says. The temp stayed exactly 
where it should of, between 175 and 185, and burned 2 or three pieces 
of wood per day, (took awile to get a good coal base). 

We decided to try running the circulator pumps only when the house 
calls for heat, hooked up the pumps to only turn on when house calls 
for heat. It works, Burns considerably less wood. The temp does get 
to about 198 at the highest that I've seen. 

Any thoughts on this?,

I understand with a slow burning fire I have more creasote buildup, 
Which I notice on the front lower of the boiler.

I understand cold weather issues, worrying about the pipes freezing 
near boiler, However if it's cold outside, the water would be running 
more often, keeping it from bursting.

I understand that it will boil @ 212, but havent come close to that 
yet.

Just wondering if anyone has tried this and thoughs people might have

Thanks


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## MS-310 (Sep 17, 2008)

There is many Ideas on if its a good idea or not. I dont like the idea for a few..

1. The water that is sitting in the pipes get kinda cold about 120 or even less. Its not good to have a 60 degree temp diff going in to the stove...Kinda will shock the sytstem also could damage the stove.

2. Say your pipes are at 120 and your coil in your furnce is 100 or so well your fan will turn on and blow cold air before getting warm. Kinda not so nice. 

3.Starting them on and off "mite" take out your pump faster.

4.How much money did you spend on makeing them turn on and off?


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## Wirenut2266 (Sep 17, 2008)

I agree with what 310 said: May shock the system from time to time. Those pumps are made to run24/7, draw very little power. Yes you may use a little less wood, but, I bet a dollar to a doughnut, your recovery time is much greater. Great idea, me, I will still go old school, plain and simple.


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## Crofter (Sep 17, 2008)

The creosote corrosion is usually greater on the fire side than that from the water side in my experience, so you will likely be shortening the life of the boiler somewhat by running it shut down.
I agree with the thermal shock issues. The greater the temperature differential the more flexing and any potential for distortion or cycle cracking over time, would be increased.


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## RodneyG (Sep 17, 2008)

I don't think your pump would last as long cycling off and on either as if it were to run 24/7. like Wirenut said their built to run24/7. Just my thoughts.


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## fletcher0780 (Sep 17, 2008)

I'd run it with the pump switched. "considerably less wood" is considerably less work. 

1. I'm not sure about the "shocking your system" with the cooler water going in, but I can't imagine it's any worse then what happens when you add water to the system.

2. You have hot water heat and not hydro-air, so MS-310's comment about the cool air is irrelevant.

3. I disagree with the comment that the pumps are meant to run constantly, the pumps that circulate the hot water through your baseboard are switch and thermostatically controlled.

4. $0 spent on changing the pump control, just have to move a wire.


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## JAL (Sep 17, 2008)

I have been running mine this way for 5 years and I haven't had any problems. The boiler stays up to temp all the time and my gut feeling is that it burns less wood. I have a CB HFSS36 which is advertised as having a Stainless Steel Firebox & Water Jacket. No Problems Yet!


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## blackdogon57 (Sep 17, 2008)

pipe76 said:


> Hi folks,
> 
> 
> We decided to try running the circulator pumps only when the house
> ...





My 6048 runs non stop. My temp is set at 175 and never goes above 185. I would be worried if it got close to 200. I run two pumps on mine as it is a big system that heats two buildings/hot water for 2 families and 1 business plus a 15000 gallon pool. I have well over 15K invested in this equipment and wouldn't risk damaging the system to save a few pieces of wood and a small amount of electricity. These pumps are finicky (Taco 009 ) I fried one by mistake last winter by cutting off the supply line by mistake. My understanding is that they are designed to run non stop. I would suggest you check with CB.


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## Crofter (Sep 17, 2008)

fletcher0780 said:


> I'd run it with the pump switched. "considerably less wood" is considerably less work.
> 
> *and burned 2 or three pieces
> of wood per day, *
> ...



Most small circulating pumps will not have a starting mechanism to be affected one way or the other by the number of startups so that is probably a wash. Typically electricity consumption might be 50 or 75 watts so maybe 20 cents or so a day for continuous running @ 12 cents a kwh. If load on the air conditioning is a concern, then continuous circulation needs to have the piping well insulated when you are running it only for domestic hot water.

It is really a shame that the waste heat from our refrigerators is not used to heat our water.


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## Wirenut2266 (Sep 17, 2008)

Blackdog: Yup your Taco Pumps are the best. Sounds like you have quite the system, would like too see. Yup pumps should run 24/7. On a regular boiler control, pumps run continuos, t-stat controls flame only. Why would I want to shut down pumps, potentially overheating firebox and buckling or cracking? No way-24/7.....If other folks boilers are shutting down pumps, they may have old controllers or modified. All new UL boilers heve red-eye flame control, never shut down pumps. Nuff said.......SAFETY REASONS


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## iCreek (Sep 17, 2008)

This is how we hooked up our Hardy OWB last year. I have talked to 10 different OWB owners around here, and they all are hooked up this way. When I mention the pump running 24/7, they just look at me like I'm stupid 

When my furnace blower first kicks on, yes the air coming from the air duct registers is cool air, but within 60 seconds I get about 115 degrees less than 2 minutes I have 120+ degrees. My FIL has been like this for 20 years, and said he never really thought of it until I mentioned the cool air when it first kicks on. The cool air is not enough to even notice a draft our anything, but I might look at testing 24/7 if I run into hot water issues with my water to water heat exchanger, it for sure would work better with a constant flow of hot water going through it. 

Up North I could see 24/7 pumps more common, fear from freezing water lines and just colder weather. 






pipe76 said:


> We decided to try running the circulator pumps only when the house
> calls for heat, hooked up the pumps to only turn on when house calls
> for heat. It works, Burns considerably less wood. The temp does get
> to about 198 at the highest that I've seen.
> ...


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## STEVEGODSEYJR (Sep 17, 2008)

When I first installed my OWB I had my pump kicking on and off. Just a few months later it was about 10 degres outside and the pump went out. Luckily my wife picked up a grundfos pump at the plumbing store. It was half the price of the taco and does the same thing. The owner advised me to" run the pump 24/7 no matter what brand it was!!!!!" He stated that the pumps were designed for that. So I run it 24/7 now.


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## LTREES (Sep 18, 2008)

Will the CB THERMO-PEX allow the water to freeze in the line? As said before, the oil boiler's taco pump spins only when there is a call for heat,so the OWB's taco won't break from on/off. Now, considering the temp in the OWB going too high, that could be a problem. In the Shaver, when the fan turns off the unit goes dormant. Does that create enough heat to bring temps up to 200 + ? When cold out the taco spins often to transfer the hot water. And how many gal. per min. does it pump? So how long to get to the heat plate? 10 sec? Adding water to the open system ( all systems give off steam, condensation. Right?) I hooked up the dom. hot water to my return line to the OWB. That will keep the temp up in the boiler and no shock or cracking. This makes sense to me, if I'm off base let me know. I guess it is mostly preference.


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## Crofter (Sep 18, 2008)

LTREES said:


> I hooked up the dom. hot water to my return line to the OWB. That will keep the temp up in the boiler and no shock or cracking. This makes sense to me, if I'm off base let me know. I guess it is mostly preference.



Can you explain this a bit more? It sounds a bit like using domestic hot water to keep your owb from cooling off.


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## itn (Sep 18, 2008)

running your pump contiously is just simple protection imo. it eliminates the possible overheating of the boiler that may not be getting adequate flow in a hotter zone. and the possible air bubble in a pump which is what usually ruins them. All you need is that one time when your wife gives you a hand and loads the cb for you- but doesn't get the door shut, and you pull in the drive 6 hrs later. i'm glad my pumps were running contiously cuz' my cb lost almost 4in of water. without the flow thru the pumps i may of had some damage i believe.


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## LTREES (Sep 18, 2008)

I took the dom hot water line, after an indirect hot water tank, put a T in it and ran it to the return line to the OWB. This is for the fill only. I put a ball valve in the line followed by back flow preventer so the boiler water does not mix. I figure that 10 gal. of hot water won't hurt me once a week. hope that helps, I


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## LTREES (Sep 18, 2008)

*itn*

So your saying that you lose alot of water with the taco pump not pumping?


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## mtfallsmikey (Sep 18, 2008)

My Taco's on the primary circuits will run 24/7, seconday circ's to the hydrocoils will run with the fan when thereis a call for heat.


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## itn (Sep 19, 2008)

*Ltrees*


my pumps run all the time. i believe it could have been worse if they had not been running.


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## mtfallsmikey (Sep 19, 2008)

The whole OWB concept....not only is it generating heat, but serves as storage as well, maintaining water temp. at the setpoint you choose. It would be awesome to be able to use on-demand circulation, outdoor reset to modulate supply temps. vs. actual heat load, but we are not there yet, and with wood burning probably never will be. With a gasification-type boiler (E-Classic, Econoburn, Tarm...) there is a cleaner burn, less wood usage, but in most situations some type of storage tank is needed since these boilers, with the exception of the E-Classic are relatively low-mass compare d to the traditional OWB. It's a small tradeoff to run a few circ's 24/7 vs. paying for #2 oil, or propane, or NG.


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## lumberchukk (Sep 19, 2008)

*Aquastat*

If you guys that are running the pump off a stat are worried about overheating the boiler why not use an aquastat as a high limit so if the water jacket gets too hot the pump will kick on. Personally i run the pump off an aquastat so that if there is hot water in the jacket the pump runs. Sure i may overheat the house some, but that's wood for ya.


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## tanker (Sep 19, 2008)

pipe76 said:


> Hi folks,
> 
> Just wanted to get people opinion on a trail setup I have. - I have a
> new Central Boiler, 6048. 130' ft from the house. My pump is located
> ...


198 degrees is awful close to the snap disc tripping.


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## ktm rider (Sep 19, 2008)

MS-310 said:


> 3.Starting them on and off "mite" take out your pump faster.



This is true. I work in a Powerhouse for the Federal Bureau of Prisons. We run the boilers, chillers, to keep the Penitentiary warm or cool. 

We run Taco pumps, very large ones but I asked the Taco rep about my little taco 07 pump i use at home and he said it would last much longer if I wired it to run continually. It would only cost a $2-$4 a month put will last much longer...


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## iCreek (Sep 19, 2008)

ktm rider said:


> We run Taco pumps, very large ones but I asked the Taco rep about my little taco 07 pump i use at home and he said it would last much longer if I wired it to run continually. It would only cost a $2-$4 a month put will last much longer...



Now this makes me want to try it... My family and friends will think I'm nuts, but it's one jumper wire on a relay at the stove. Oh, so tempting !!! 

plus I will be guaranteed hot water at my water to water plate exchanger for sure...


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## HardyOWB (Sep 20, 2008)

I will be giving it a try as well. Mine is set up to kick the pump on and off when the termostat turns the hot air furnace on. I have had it set up this way for the last 2 years, and that is how the dealer recommended it. I will be trying the continuous method this winter.


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## Lloyd H (Sep 20, 2008)

*circ pumps*

Mtfallsmikey has the right answer, run the main loop pump continuosly and cycle the local pump with the fan, a second local pump on the domestic hot water will keep it from overheating also.


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## LTREES (Sep 21, 2008)

HardyOWB said:


> I will be giving it a try as well. Mine is set up to kick the pump on and off when the termostat turns the hot air furnace on. I have had it set up this way for the last 2 years, and that is how the dealer recommended it. I will be trying the continuous method this winter.



How hot did the water temp get in the OWB the past 2 years? Or is this just a precaution?


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## Guitarguy139 (Jan 28, 2020)

So this is resurrecting an old thread but it was the only one that came up when I was researching my plans. For anyone still looking to do this but keep your pump running I installed a differential bypass valve at my boiler for two of my buildings. A solenoid valve is powered by 3 relays for each device that can call for heat. Works like a charm! Has helped out alot with how much wood I use.


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