Coal Boiler to Oil Boiler Do Want the Circulator to Run Cons

If I hook my boilers up parreal to each other does the cirrulator run full time between the 2 boilers? would it not be better to have it shut off when the boilers are up to temp? won't teh boilers cool down faster by circulating the water between the 2 when there is no call for heat? KA 6 boiler

the way I understand it, if you hook up your boilers in parallel you do NOT circulate water between them. This would be a waste of heat up the chimney in the oil boiler.

If you want to use all the controls off the oil boiler, but yet supply the oil boiler with hot water from the coal boiler, then you'd use a B aquastat to start circulation when the coal boiler is up to temp. It would also stop circulation if the coal boiler cooled off.

Otherwise, you'll have to use some relays to do things differently.

stoker-man wrote:If you want to use all the controls off the oil boiler, but yet supply the oil boiler with hot water from the coal boiler, then you'd use a B aquastat to start circulation when the coal boiler is up to temp. It would also stop circulation if the coal boiler cooled off.

Otherwise, you'll have to use some relays to do things differently.

ahhh, yes I was assuming that you were hooking up in parallel to eliminate the oil boiler from the heating loop of the house. That's what I'm doing.

You could just jumper the aquastat (TT) on the coal boiler to always call for heat. Once it reaches operating temp, the circulator will start. If the fire fails and the temp drops it will shut off.

I thought that the Circulator is suppose to run constant, is parallel better then series, what is the diffrence. I know I asked this before bu know I am confused. Thanks

You'll have to determine if you want to use two boilers, or just one, and circulate between the two. If you choose the latter, you can shut down the stoker when you want to go on vacation and just use the existing boiler. Otherwise, you can use the oil boiler with all its controls and circulate between the two, or use the stoker and hook up all the necessary piping and run each as desired, independently.

I want th eoil boiler to kickin if something were to happen to the coal boiler or if I were to go away on vacation, so I was planning on runing the coal boiler though teh oil boiler, would I need to keep the circulator running all of the time then?

There would have to be some kind of electrical communication between the two units, otherwise, if there was no demand for heat by the oil boiler's controls, the coal unit would shut down on it's high limit.

efm's wood/coal manual boiler uses a dump zone to unload excess heat when the oil boiler doesn't take away the heat on warm days. It's just a B aquastat that causes a circulator to run when a high limit is reached on the wood/coal unit and dumps heat into one of your pre-chosen heating loops.

I don't think I've seen any wiring diagrams for two controlled units working together like you'd like to do, but I'm sure with the proper aquastats and relays, it could be done.

JOE.G wrote:I want the oil boiler to kick in if something were to happen to the coal boiler?

How it would be wired would depend on how it is plumbed.

Ok, now this thread has got me totaly confused, I though that I would run my coal boiler though my oil boiler in a loop coal out into the oil in and back, and that when a call for heat happen the zone vavles and the circulator on my current oil boiler would kick on and the heat the house and the oil boiler would not kick on becasue the hi and lo would be set lower then the coal boiler. If for some reason it did get below the low limit of the oil boiler the oil boiler would kick on then. But in a set up like this would I need the coal boiler circulator that only circullates between the to boilers need to run when there is no call for heat and the oil boiler and coal boiler are up to temp?

OK, just wire the TT terminals on the coal aquastat to get power from the thermostat transformer, this in esscense gives you a continuous call for heat. Once the coal boiler reaches operating temperature the circulator (wired to the same aquastat) will start and continue to run until the coal boiler fails. Keep in mind, most of these control transformers are wired directly to the original appliance and shutting the service switch off will kill the signal to the coal boiler too. You could just install a similar transformer on the coal boiler to eliminate this if it is a concern.

I have the exact setup in my house that you are describing, only right now I have a wood boiler in the system instead of a coal boiler. I run the circulator between the two boilers continuously and have had good luck with it. The impact on my electric bill is not all that significant. I am replacing the Wood Boiler with a Keystoker unit which I orderd in April and was delieverd in June. Been busy with other projects and am now just installing the Keystoker. Any one want to buy a used wood boiler.

The circulator that moves the water between the two boilers is located near my oil burner and my house has 2 zones. How would I wire this so the circulator that moves the water between the two boilers comes on when either of the zones calls for heat?

One warning about jumping TT: Make sure there are no thermostat wires hooked up when you do it because you will probably fry the heat anticipator in the thermostat.

AdkCoal wrote:I run the circulator between the two boilers continuously and have had good luck with it.

The circulator that moves the water between the two boilers is located near my oil burner and my house has 2 zones. How would I wire this so the circulator that moves the water between the two boilers comes on when either of the zones calls for heat?

Do you mean the circ pump on the original primary boiler? I hope so as you state the coal circ is already running. You shouldn't have to do anything, it is already wired into the thermostat and aquastat on the primary. It should start the second pump on a call for heat as it would normally. You should not need any interboiler wiring.