Convection starts un the thermal store and the momentum of said convection will cause this.
2 port valve will sort it.
2 port valve will sort it.
I do not know if the pump is running. I suspect it could be. Why else would circulation take place. At that across a horizontal pipe run.Of course, but if it's not running, does it matter?
I suppose if it's a nice quiet pump, and an oldish one without any LEDs, it could be running without the OP knowing, but it seems unlikely. If the boiler is higher than the HW cylinder there could be convection, we need the OP to confirm layout. He said there are vertical pipe runs, so it's either above or below!I do not know if the pump is running. I suspect it could be. Why else would circulation take place. At that across a horizontal pipe run.
Interesting, but there's been no indication from the OP that it's a back boiler conversion. If it is, and it's a system boiler, that could be the problem. He only said it's a Worcester boiler, we don't know whether it's heat-only or system. He's said he has no motorised valves. He has a cylinder stat, be good to know how the system is controlled. Adding a 3-port valve and updating the controls (depending on more detailed information) would improve the system, and fix his current problem.Side note. Two days ago I was disconnecting a fire that was to be removed to make place for a log burner. This fire was installed at some point after the back boiler was removed and a combi fitted elsewhere. Fixitflav, pay attention here……
to left of the fire under the flooring where I was to disconnect the gas pipe, would you believe there is a pump that is wired up but not in use? The pump that is operational is in the boiler. Unused pump use to be operational for the back boiler. To a lay person touching this pump, they would say the pump is not running but the one in the boiler could be heating the rads.
Until all the facts are known, and a site visit is carried out, any speculation will be based on work experience And not idle speculation.
Thanks Jeff, but, excuse my ignorance, how does the 2 port valve work? The boiler provides heat only to the thermal store. DHW and CH source their heat from the thermal store. They are not connected to the boiler.Convection starts un the thermal store and the momentum of said convection will cause this.
2 port valve will sort it.
Why do you think using electric in summer for the HW is cheaper? Have you taken readings to compare with gas? Electric costs about 4 x gas per kWh, and though nearly all the electric power goes into the water, gas has some losses due to boiler efficiency and pipework heat loss, it's unlikely to turn out dearer. But gas has the downside of heat loss in hot weather might make the house too hot.Thanks again for all the comments.
Some details of the system:
Boiler: Worcester Greenstar 8000 Life. LPG. (Sealed system) Only heats the cylinder - no other function.
Thermal store: McDonald Thermflow 250l with F & E tank. Vented
Both units are installed on the ground floor with the boiler mounted slightly higher than the boiler flow connection on the cylinder. There are no external valves in the flow and return pipework between the two units. The 22mm pipework runs from the boiler vertically to the first floor where it runs (under the floor) to the point where it runs vertically down to the cylinder. The flow and return run in parallel. The length is approx. 10m
Electrically, there is one supply only to the boiler panel. There are no other electrical feeds to the boiler. When powered on the boiler is controlled by a stat via a Danfoss programmer which takes its power from the boiler panel.
Normally, in winter months the system works and controls well with no issues. It is less than 2 years old.
In summer, to save costs, the boiler is switched off at the local isolator AND at the db (to avoid it being switched on inadvertently). The immersion heater is then used to heat the cylinder for DHW.
Following some of the earlier comments, I’m now of the opinion that convection is the cause of hot water circulating through the boiler. But.... how to stop it?
Are these valid options? :
1. Drain the system - this means refilling at the end of summer and adding inhibiter?
2. Installing isolation valves in the pipework - I believe this is a BIG no-no (and possibly illegal?)
Thanks again.
It doesnt matter the valves are still where I already told you they were, just close the flow valve 20 second jobThe 22mm pipework runs from the boiler vertically to the first floor where it runs (under the floor) to the point where it runs vertically down to the cylinder. The flow and return run in parallel. The length is approx. 10m
He hasn't said anything about unwanted heat at the radiators, only the boiler to cylinder pipework.Cylinder is heated by immersion heater but issue with wiring or control ( sticking relay perhaps??) activates the CH PUMP resulting in heat to radiators.
AgreedNo heat is coming from the boiler as it is not powered.
If my theory is correct, a check valve on the boiler pump would stop the (backward) convection, so there isn't one.It is not uncommon for pump to be fitted with check valves- do not know if that is the case.
He says "Both units are installed on the ground floor with the boiler mounted slightly higher than the boiler flow connection on the cylinder." Though just what the levels are isn't clear.Cylinder is on upper level. No convection possible to lower floor, nor to same level
Convection to the rads isn't the problem.nor to same level as rads will almost certainly not support convection circulation.
Not with you. That's the pipe that's getting hot when it shouldn'tPipe run boiler to cylinder is immaterial in this case.
Boiler demand to control motorised valve and the end switch to fire the boiler.Thanks Jeff, but, excuse my ignorance, how does the 2 port valve work? The boiler provides heat only to the thermal store. DHW and CH source their heat from the thermal store. They are not connected to the boiler.
Suggest you look at the manual for the cylinder.If my theory is correct, a check valve on the boiler pump would stop the (backward) convection, so there isn't one.
Please explain how the operating details of the cylinder affects the OP's problem - pipes between the boiler and cylinder getting hot when the cylinder is heated by electric?Suggest you look at the manual for the cylinder.
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