2 heat sources - 1 pump. How to wire the pump control?

[NjonesFermoy]

Hi guys - I've had a quick search through the forum & can't find the answer to my issue, so please forgive me if its been asked before & I missed it!

I've just installed a solid fuel stove with a back boiler in my house and its been plumbed into the existing heating system right at my oil boiler - eg the return pipe to the oil boiler was re-directed to the stove & then the return pipe from the stove goes back into the oil boiler - just extending the circuit.

SO - the original circulating pump is still in place & is currently switched on 24/7 until I've figured out how to properly control it!

The circulating pump needs to power on either when the oil boiler is powered up OR when the pipe stat on the stove heats up. It needs to be activated regardless of which input requires it, or even if they both do, and only switch off if there is no power from either,...

How do I do this??!

Many thanks in advance for your help.

 

[Richardthe3rd]

Hi guys - I've had a quick search through the forum & can't find the answer to my issue, so please forgive me if its been asked before & I missed it!

I've just installed a solid fuel stove with a back boiler in my house and its been plumbed into the existing heating system right at my oil boiler - eg the return pipe to the oil boiler was re-directed to the stove & then the return pipe from the stove goes back into the oil boiler - just extending the circuit.

SO - the original circulating pump is still in place & is currently switched on 24/7 until I've figured out how to properly control it!

The circulating pump needs to power on either when the oil boiler is powered up OR when the pipe stat on the stove heats up. It needs to be activated regardless of which input requires it, or even if they both do, and only switch off if there is no power from either,...

How do I do this??!

Many thanks in advance for your help.

It's not normal to link two boilers in this manor, firstly you may well have circulation through a redundant boiler & secondly it maybe dangerous if the solid fuel boiler overheats. There's a few ways to correctly connect two appliances, one of the most popular ones being a Dunsley Netralizer.
HTH

 

[Norcon]

The most important design requirement is the thermo siphoning circuit!

 

[muggles]

How do I do this??!

You start by removing the setup you've just installed and piping it up correctly. A solid fuel appliance cannot rely on a pump for circulation, as it will become dangerously overheated in the event of a pump failure or a power cut - it must rely on gravity circulation alone. Piped up as you've described it, there is a very real risk of the water flashing to steam and the whole lot exploding, which will most probably demolish your house.

The two systems can be linked by either installing a Dunsley neutraliser as has been suggested, or a thermal store. Make sure your loft tank is of a type that is capable of storing boiling water without splitting - if it isn't and an overheat occurs, the tank will split and you'll end up with near-boiling water cascading through your house, which can quite easily kill someone. There may also be a need to install a heat leak radiator circuit to dump excess heat

 

[NjonesFermoy]

Fear not Muggles - the system has of course been designed with this in mind. there is a small gravity fed system attached to the stove (sufficient to prevent boiling - tried and tested in the storms this winter) which is disconnected via an electronic valve - should power fail, this valve opens & the system becomes gravity fed.

It really is quite simple.

Anyway - I asked the same question in the electrical section of this forum where at least one member was more helpful than you grumpy lot - - the answer I got was perfect in its simplicity and very easy to implement:

How do I do this??!

You start by removing the setup you've just installed and piping it up correctly. A solid fuel appliance cannot rely on a pump for circulation, as it will become dangerously overheated in the event of a pump failure or a power cut - it must rely on gravity circulation alone. Piped up as you've described it, there is a very real risk of the water flashing to steam and the whole lot exploding, which will most probably demolish your house.

The two systems can be linked by either installing a Dunsley neutraliser as has been suggested, or a thermal store. Make sure your loft tank is of a type that is capable of storing boiling water without splitting - if it isn't and an overheat occurs, the tank will split and you'll end up with near-boiling water cascading through your house, which can quite easily kill someone. There may also be a need to install a heat leak radiator circuit to dump excess heat

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• NjonesFermoy
• 23 Jan 2014
• 1

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• NjonesFermoy
• 23 Jan 2014
• 1

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• NjonesFermoy
• 23 Jan 2014
• 1

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• NjonesFermoy
• 23 Jan 2014
• 1

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• NjonesFermoy
• 23 Jan 2014
• 1

 

[muggles]

We're not being grumpy, we were just concerned for your safety based on the information you presented. We weren't to know that you'd only given us half the information. Without knowing your testing methods I can't comment on that of course, but if you're happy with a solution presented to you by people who aren't plumbers then good luck to you...

 

[Norcon]

Post up a plumbing circuit schematic.

With two heat sources and one circulator you will likely have one boiler constantly acting like a radiator and wasting heat up the flue.

Also as you have no return stat (the most important one) , cold glugs of water from the heating system will enter the stove return creating acid condensation inside the stove , tarring the chimney and making the stove just basically very inefficient and reducing its lifespan.

And will reduce the heat output to the room the stoves located in also!

The cold feed should have a clear path to the stove boiler return tapping and the vent a clear path for venting.

The gravity circuit must remain cycling at all times!