hydronic heating circulator question


First time poster...avid reader. In november the oil furnace tech came to do the annual inspection and cleaning. Apparently, he needed to replace the transformer, which he did. So the other day I happen to be down near the furnace and notice a humming sound. It is the circulator pump. It seems even with the heat side of the boiler off, the pump is still running. It never used to be that way. When we turned the heat off, the pump was off as well. It also looks like something is missing. Just from memory, I think there was either a relay or a seperate transformer wired in before the pump to prevent it from running all the time. Does anyone know what is missing and hoe it's supposed to be wired in. I would call the oil company again but were in the country and don't have a choice who to use and I don't like who were stuck with. I really don't want to pay for another service call. Thanks, Rick Almost forgot... it's a John woods JWF 307V boiler White-Rodgers 8A05A-101 transformer Grundfos pump thermostat is wired to the R and G terminals of the transformer, Com is open
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Mine is wired so that the thermostat applies power (24 vac) to a relay. The relay starts the boiler (flame) and applies 120 vac to the circulator motor. The circuits are simple and you should be able to figure them out. It sounds as if the relay thinks a thermostat is "on" all the time. Get out your meter! Use a clip lead to simulate a contact closure.
Rick wrote:

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transformer that isn't there anymore. Stubby wrote:

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The guy wired the circulator pump hot all the time so it won't shut off. Can I wire in a seperate 24V transformer to the thermostat terminals directly to the circ. pump? Rick wrote:

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You could wire it to a separate relay, however the relay you have is a double pole relay and should be able to control the circulator. If the thermostat does not control the circulator, I'd call the service company back and correct their mistake

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There are variables, depending upon the specific equipment, but in general, if you only have the one circulator pump, and one heat zone, the thermostat should control the circulator. Thermostat up-pump comes on, thermostat down-pump goes off. The boiler may be started by the same relay that controls the circulator, or it may just start and stop to maintain a predetermined boiler temperature. In any event, the boiler will go off when the water temp reaches its limit of around 190 degrees, if the room thermostat , which controls the circulator is not satisfied at that time the circulator should continue to run

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There's no reason why it needs to be that way, really.

You don't necessarily have a problem. The circulator and the boiler operate more-or-less independently. The circulator runs when the thermostat calls for heat; the boiler runs when the water circulating through it is cooler than the boiler's cut-in temperature. It's perfectly normal for the circulator to continue running after the boiler has shut off -- or for the circulator to start running before the boiler turns on -- as long as the water is hot.
Do these two tests with the boiler switched ON:
1. Turn your thermostat(s) down to several degrees below room temperature. The circulator should stop promptly. If not, there's a problem.
2. Turn the thermostat(s) back up to several degrees above room temperature. The circulator should start up promptly, followed quickly by the boiler. If not, there's a problem.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Rick wrote:

Get thee a basic book on Hydronic heating and controls. From the sound of things, you will be needing it to forestall another visit from this tech.
Look in your local libray, BigBox or Amazon.com maybe. Audels has some good ones.
Jim
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Forestall a visit? I want to prevent a visit. I can't stand this tech or the company. The only thing they ever do correctly is put the oil in the right hole. And bill us. Speedy Jim wrote:

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