central heating wiring question

gorwanvfr

Thinking about wiring in a room thermostat, my question is when the thermostats contacts open and cut the boiler out should the circulating pump also stop or should it keep running?
Thanks

davelerave

afaik you can fit a run-on stat with changeover contact for a simple boiler/pump arrangement .the common goes to pump and other 2 connect to timer/stat and perm. feed (from heating spur)

eoghan.geraghty

If you are talking about breaking the supply to the boiler through the thermostat and not using a motorised valve, you would need to feed the pump seperately from the timeclock to keep the pump running, otherwise pump will cut out with boiler.

Is this what you are trying to do?

Most of the new boilers I've worked on lately don't recommend this, they want you to feed a stat from the internal interlink, and feed the boiler with a permanent supply. Check your boiler manufacturer instructions first.
If your boiler has an internal interlink, this should give you the pump overrun you need.

davelerave

it may not be relevant for the modern systems with a call loop ,but was used on older systems with oil boilers.A pipe stat on the return pipe to keep the pump running until water cools down sufficiently

youtheman

When the room stat confirms that the desired temperature is reached it turns off the gas valve within the boiler (thus stopping the gas burning). But there is still a loads of 'thermal energy' in the all the hot water within the system, so it makes sense to continue circulating the hot water, so you're using up this 'free energy'. You are also allowing your boiler to cool down in a controlled manner, and noy subjecting it to 'thermal shock'.

I agree with the post by Eoghan Geraghty. You need to refer to the boiler manual. I'm sure you will find that the boiler needs a permanent supply (and this is used to control the pump via the internal boiler logic). There will also be a spearate link to control an external volt free contact (for the room thermostat).

davelerave

Not all boilers are gas:D
Never worked on one as mains gas not available.The run-on stat would have been common for standard oil-boilers pre-call loops. All depends what the op has

gorwanvfr

davelerave wrote: »

Not all boilers are gas:D
Never worked on one as mains gas not available.The run-on stat would have been common for standard oil-boilers pre-call loops. All depends what the op has

It's an Firebird oil boiler that is fitted, the only thermostat in the system is the one on the boiler itself. Was thinking about fitting a wireless thermostat but looking at the wiring diagram it looks like when it turns the boiler off it would also kill the power to the pump. At the monent the system is wired as such. The timer is in the house and it sends a signal out to the boiler and pump via a hard wire. This wire is split in to two one side goes to the boiler thermostat (which then goes to the burner) and the other side/wire goes to the pump.

yoshytoshy

gorwanvfr wrote: »

It's an Firebird oil boiler that is fitted, the only thermostat in the system is the one on the boiler itself. Was thinking about fitting a wireless thermostat but looking at the wiring diagram it looks like when it turns the boiler off it would also kill the power to the pump. At the monent the system is wired as such. The timer is in the house and it sends a signal out to the boiler and pump via a hard wire. This wire is split in to two one side goes to the boiler thermostat (which then goes to the burner) and the other side/wire goes to the pump.

You could leave the pump connected the old way and just wire the wireless stat into the switch for the boiler.

davelerave

gorwanvfr wrote: »

It's an Firebird oil boiler that is fitted, the only thermostat in the system is the one on the boiler itself. Was thinking about fitting a wireless thermostat but looking at the wiring diagram it looks like when it turns the boiler off it would also kill the power to the pump. At the monent the system is wired as such. The timer is in the house and it sends a signal out to the boiler and pump via a hard wire. This wire is split in to two one side goes to the boiler thermostat (which then goes to the burner) and the other side/wire goes to the pump.

.
if the boiler/pump is outside you prob need an additional core (perm feed from heating spur) for changeover pipe stat.

gorwanvfr

yoshytoshy wrote: »

You could leave the pump connected the old way and just wire the wireless stat into the switch for the boiler.

So simply its brillant why didn’t I think of it

davelerave

If you changed to 'wireless programmable stat' you will have the permanent
feed at boiler/pump location for run-on pipe stat.
With 'standard wireless stat' and existing timeclock the run-on stat wont work with timer off

yoshytoshy

gorwanvfr wrote: »

So simply its brillant why didn’t I think of it

You can buy a danfoss single reciever and stat pack ,break the live for the boiler with the reciever.
The pump will only run when the clock is timed to be on ,so it should be fine like that.

davelerave

yoshytoshy wrote: »

You can buy a danfoss single reciever and stat pack ,break the live for the boiler with the reciever.
The pump will only run when the clock is timed to be on ,so it should be fine like that.

Pump may be running for long periods if stat off,and no run-on when timer switches off!
I would think 'wireless programmable stat' or additional permanent feed for complete solution:D

yoshytoshy

Yeah .