Circulating Pump Running Continuously

Hi,
This is my first tme posting to this forum. I hope you can help me to learn what my issue might be.
The current problem is that the circulating pump seems to run constantly. I'd like to learn what could be causing this.

My problems started recently with the furnace coming on like it should, but the house was getting too hot. It was as though the furnace was not responding to the "that's enough" signal from the thermostat. I tried replacing the thermostat, but the problem persisted.

I called a repair service to come out, and they determined that it was the aquastat that was the problem. But they also questioned my telling them that it was a 2 zone system, because they said there was no second valve.

Long story short - aquastat replacement didn't fix the problem, and a second valve was found. Technician said that this valve was leaking, and that was stuck in the open position, causing the overheating of the house.

The valve was replaced, and the house is no longer overheating - but the new problem is that now the circulating pump is running practically non stop.

The system is an oil-fired boiler, forced hot water (hydronic?) baseboard (fin) heating system. It's old, but has been well maintained.

The circulating pump was replaced in 2004, it's a Taco.
The Aquastat is a Honeywell L4006A.

I don't remember the circulating pump running on and on the way it does now...even when there is no hot water circulating...(baseboards are cold - boiler is off).

Any ideas on what the issue could be? Is it bad to let it just run? (I've been turning off the system, rather than just let it run).

Thanks.

 

Most systems that have a single circulator and zone valves use what is called an "end switch" in the zone valve to control the circulator via a circulator relay or sometimes through the aquastat.

It sounds to me like one of your zone valves is not opening the end switch when the thermostat is satisfied or perhaps there is a wiring problem between the zone valves and the circulator relay / aquastat.

It also sounds like you need a new service company.

 

Thank you Furd. I truly appreciate your help. Can you tell me if I should continue to shut off the boiler, rather than let the pump continuously run? Is it harmful to allow the pump to continuously run? I have called another company, and they will be out on Monday, so I just need to know how to manage until then.
Thanks.

 

The circulator running continuously probably won't be harmed but if it is not too inconvenient it is probably better to shut it down manually as needed until it is properly repaired.

 

Gracie, just so that that furd (who is a great contributor here) can feel much better about disagreeing with me at a later date, some people just have their circulator on a switch. I did.

You switch it on when heating season starts and off when it ends. Circs don't tend to use and inordinate amount of power so don't fret about just leaving it on until you are able to find out why things have changed.

Continuous circulation is actually better for comfort.

 

Thanks very much Furd and Who - good to know that I'm not burning out the pump - or creating other damage/issues if I leave it on.
I think I'll continue to shut whole system off at night - and put it back on during the day - new svc co coming monday morning.
hopefully it's a simple wiring issue...

 

Gracie, just be careful about leaving your system off for too long, especially is you have exposed pipe along outside walls where it doesn't have the best insulation. I know I have some runs like that up to the bedrooms... luckily brick is better than just a simple R value would tell you. That said, you run far less rick of any freeze-ups just by leaving your circ on. That circ would prefer staying on rather than turning off and on if the truth be known. It's just a matter of question as to whether the electrical savings and life cycle costs are relative to one another.

If you have pipes in any outside walls, just leave the circ on, rather than shutting it all down overnight.

What kind of circ is it? Can you read the stamped plate on it that has the electrical information... or just make and model?

 

Thanks - I do have pipes that run along the outside walls, along the ceiling of the (unfinished/unheated) toolroom in the basement - right under the bedrooms - so I appreciate the advice - and the circ is a Taco - it was installed in 12/2004.

 

What model of Taco is it? If it's a 007 then letting it run all the time isn't costing much at all.

 

My concern about letting a "cartridge" pump run continuously would be if you had positive shutoff zone valves. The cartridge pumps use flowing water to help cool the motor and with no water flow there is a slight possibility of overheating the motor.

Otherwise, Who is correct about some systems having continuously running circulators. When I was gainfully employed I had several circulators (up to 25 horsepower) running 24 / 7 with no problem.

 

Woops -- Good point on the zone valves furd... I wasn't thinking about the deadheading at all... I'm still a single zoner and I'd never use zone valves but really need to think about those that do before posting.