Boiler and stove electrical interlock-HELP!!!

daludo

Hi all,need some urgent help.i have just wired a standard 3 zone heating system.However the plumber has now installed a stove c/w pipe stat and pump.all wired and working fine.however the plumber wants the ds zone valve to come on with the pump when the pipe stat calls for it.i know this involves a relay to interlock the boiler.ive done it before but my brain has gone into meltdown and i just cant get my head around it.any ideas or drawings ye could enlighten me with would b greatly appreciated,have to get it done in morning,thanks in advance

Tuco88

Are you looking for an electrical interlock between both of them? I remember I had to use "systemlink" to tie in a vented boiler system to the pressurised heating system, be careful what you do, can be very dangerous if unvented the stove.

daludo

Tuco88 wrote: »

Are you looking for an electrical interlock between both of them? I remember I had to use "systemlink" to tie in a vented boiler system to the pressurised heating system, be careful what you do, can be very dangerous if unvented the stove.

He said he just wants the ds zv to open to dump the hot water from the stove,he did mention a relay to interlock the boiler/stove.i presume an 11pin relay and then the fun starts?

Bruthal

You get a relay. Stove pipe stat brings on stove pumps, and also a relay which has normally closed contacts. Put a closed contact of the relay into gas/oil boiler control loop.

When stove pipe stat closes, the closed contact on relay opens, disabling the boiler.

Another relay is needed to independently energise any motorised valves from the pipe stat also.

I used the heat genie to tie a stove to my gas heating, and used the system link setup. But I added my own relay to enable the stove pipe stat to energize the heating and hot water motorised valves. And a relay in the system link to lock gas boiler out because any motorised valve closing its contacts brings on the gas boiler. But it can easily be done with 2 relays.

daludo

Thanks bruthal, will I get away with one 11 pin relay or just stick 2 8 pins side by side.I'm beginning to see light at d end of the tunnel :-)

Bruthal

One relay will do if only switching on one zone valve with stove. So use normally closed contact in gas boiler control loop, it can simply go in series with zone valve switches if they are propey controlling the gas boiler.

Then use normally open contact of separate pole in the relay to switch on the zone valve. But it depends exactly what you want to happen, as to the setup of relays.

In my setup I have 2 motirized valves. So I used both poles of a relay to energise them when the stove pipe stat brings on the stove pumps, so when the stove is lighting, it opens both valves. And another relay disables gas boiler.

beanie10

This does not sound right. First there should not be any restrictions on a stove heating circuit ie motorised valve or valve of any kind apart from blow off valve. What happens if valve fails?
Second is stove circuit should be plumbed in a way that does not require an electrical valve to open.
I'm sure the above ways will get it to work but there should not a valve on the heating circuit.
IMO plumber has this wrong and not safe.

Bruthal

beanie10 wrote: »

This does not sound right. First there should not be any restrictions on a stove heating circuit ie motorised valve or valve of any kind apart from blow off valve. What happens if valve fails?
Second is stove circuit should be plumbed in a way that does not require an electrical valve to open.
I'm sure the above ways will get it to work but there should not a valve on the heating circuit.
IMO plumber has this wrong and not safe.

Depends how its done. I have the stove linked into the sealed gas heating system via a heat genie. Wouldn't be much good if you needed to remove zone valves etc from the existing system.

If it's a stove directly heating rads and cylinder, then the cylinder circuit should be a fully open gravity circuit with no devices on it. The radiator circuit relies on a pump and won't usually work properly during power failure anyway. A heat leak radiator can be used to counteract the power loss scenario as once the cylinder is heated, the gravity circuit also stops flowing.

beanie10

Bruthal wrote: »

Depends how its done. I have the stove linked into the sealed gas heating system via a heat genie. Wouldn't be much good if you needed to remove zone valves etc from the existing system.

If it's a stove directly heating rads and cylinder, then the cylinder circuit should be a fully open gravity circuit with no devices on it. The radiator circuit relies on a pump and won't usually work properly during power failure anyway. A heat leak radiator can be used to counteract the power loss scenario as once the cylinder is heated, the gravity circuit also stops flowing.

Any stove system is dangerous in a power loss situation unless you run the hot taps and close the stove off. The heating circuit will never work with a power loss as pump will not run.
The problem with OP system, from what I can see, there is a constant restriction on on the heating circuit as the flow through the open valve will be reduced. This will effect the efficiency of the stove as water cannot leave the back boiler as quickly as it should.I wonder is the stove even piped in inch pipe?
But if that motorised valve fails the onwer has no way of knowing until back boiler explodes.
At least in a power loss situation the owner knows the stove needs to be closed off.
I only know this as I was working in a house once and a plumber was in disbelief of a manual valve at the stove. He promptly removed it.

Bruthal

beanie10 wrote: »

Any stove system is dangerous in a power loss situation unless you run the hot taps and close the stove off. The heating circuit will never work with a power loss as pump will not run.

The gravity circuit works without pumps, but stops when cylinder is heated.

A heat leak radiator of suitable size will work with power loss.

Stoves have the vent to expansion tank.

The problem with OP system, from what I can see, there is a constant restriction on on the heating circuit as the flow through the open valve will be reduced. This will effect the efficiency of the stove as water cannot leave the back boiler as quickly as it should.I wonder is the stove even piped in inch pipe?

Inch pipe is used to help encourage gravity flow due to convection, Its not that size to allow quick enough flow to radiators or from stove. The flow rate around the 1 inch gravity circuit will be slow enough.

But if that motorised valve fails the onwer has no way of knowing until back boiler explodes.

We don't know how its plumbed. My one for example, is perfectly reasonable to have standard motorized valves on the gas system, even when the stove is heating it.
I have inch pipes to heat genie, and 3/4 from it to gas system, and them 3/4 pipes handle all heat transfer from heat genie to rads/cylinder, via motorized valves on the gas system. Heat genie inch pipes help with gravity circulation between stove and it, before pipe stat beings on 2 pumps.

Another system I did last year has inch pipes to cylinder coil, no valves, and 3/4 to radiators via pump, again no valves. 4 ports of stove used.

Fully vented, no explosions....
At first only one radiator on it. No problems.

At least in a power loss situation the owner knows the stove needs to be closed off.
I only know this as I was working in a house once and a plumber was in disbelief of a manual valve at the stove. He promptly removed it.

Properly plumbed, it will be safe.

Manual valve at stove is no properly plumbed anyway.

The op situation is not perfectly clear

Tuco88

Depending on the stove you have, you can use 3/4" pipe. If you have the four ports, two for rads two for cylinder. My system is 2 inch pipes because of my location, gravity fed primary circuit, and a circulation pump for the rads on the return simple stat adjustment for warmer water.

I agree there should be no valve on the gravity circuit to the stove it's too Risky. The expansion pipe is not much good if it's placed before the valve if the valve fails. There's no risk if the pump fails, the stanley and aga ranges heated cylinders for years with no pumps/heat sinks, unless you have a horrid system. Surly any decent plumber will place a 3 bar SRV on the stove.

I agree with Bruthal the heat genie/system link take care of all the problems above.

Fitting a stove to a gas heating circuit should only ever be done when using a recognised system like a heat genie or system link anything else is not recognised by gas boiler manufacturers which can impact on warranty and the installer has no protection in the event of a incident as all gas installions must meet a given criteria.

Calahonda52

beanie10 wrote: »

This does not sound right. First there should not be any restrictions on a stove heating circuit ie motorised valve or valve of any kind apart from blow off valve. What happens if valve fails?
Second is stove circuit should be plumbed in a way that does not require an electrical valve to open.
I'm sure the above ways will get it to work but there should not a valve on the heating circuit.
IMO plumber has this wrong and not safe.

This is not perhaps entirely correct. Depends on your definition of circuit.:)
The safety aspect that is at issue here is what happens when the power dies just after you have the stove going full blast with a load of coal?

The outlet from the stove must go straight up as an expansion pipe and loop back into the header tank.
The rad circuits can be teed from it, not visa versa
Likewise, the cold water feed from the header tank must tee vertically downwards into the return pipe to stove just before the stove so as there are no restrictions.
The header tank should be sized accordingly, with plenty of head room.
The return pipe should be minimum 22mm and the flow from boiler ideally should be 25mm, certainly for the last vertical stretch and the bend around into the header tank as the larger diameter will slow down the rush of boiling water and steam.

Dtp1979

Calahonda52 wrote: »

This is not perhaps entirely correct. Depends on your definition of circuit.:)
The safety aspect that is at issue here is what happens when the power dies just after you have the stove going full blast with a load of coal?

The outlet from the stove must go straight up as an expansion pipe and loop back into the header tank.
The rad circuits can be teed from it, not visa versa
Likewise, the cold water feed from the header tank must tee vertically downwards into the return pipe to stove just before the stove so as there are no restrictions.
The header tank should be sized accordingly, with plenty of head room.
The return pipe should be minimum 22mm and the flow from boiler ideally should be 25mm, certainly for the last vertical stretch and the bend around into the header tank as the larger diameter will slow down the rush of boiling water and steam.

Both pipes from the stove must be 1". The pipe that goes from the flow up to the expansion tank is the vent, not the expansion. The " cold feed " is the expansion and it is piped in front of the pump