Back boiler stove not heating radiators

WindWarrior

I have an oil burner and solid fuel back boiler system in the house. The back boiler has stopped heating the radiators a few days ago. When fire is on it it heats the water in the HW cylinder but not the radiators. The oil burner is working okay and heats the radiators upstairs and downstairs. I have checked the thermostat and the motorized valves and they are working okay. The circulation pump is also working and and have bled it just in case if air in the system. Would anyone have any ideas of what the issue could be? I called my usual plumber and explained all the above but he can't come till after Christmas. Thanks

Wearb

Maybe a stuck one way valve. Also there are times when pump running but not circulating water. Is the pipe at both sides of the pump getting warm.

Maybe also try giving the one way valve a tap.

WindWarrior

Pipes both sides of the pump are hot. The top side is copper and feels hotter than the bottom side which is plastic pipe. Is the non return valve the fitting at the bottom side of the pump with an arrow pointing down? I gave it a few taps there. The circulation pump is very hot at the moment.

Wearb

Without a pic, that's most likely the valve.

Lazy/ broken circulation pumps can be difficult to diagnose. It's usually a matter of ruling out everything else, then that's what you're left with.

jimf

https://www.boards.ie/discussion/comment/119981016#Comment_119981016

try and get somebody to have a look at this issue asap

your comment that the top side is copper and the bottom side is plastic is a big worry

WindWarrior

I actually replaced the pump myself today to rule it out but that obviously wasn't the problem. I'll see can I post a picture. Thanks for the help

WindWarrior

I meant it's plastic below the non return valve. Copper into the pump

WindWarrior

IMG_20221210_202755.jpg

Picture of set up

Furze99

Presume it's a bungalow and pump needed to circulate? If you have radiators upstairs they should heat by natural flow. You changed the pump today, presumably drained and refilled the system. Any chance of an air lock somewhere? Have you filled and bled all the rads, have them turned on? Is the pump operating, you should be able to turn it on and hear it working by adjusting thermostat that controls it. How far can you trace the hot water in the flow circuit to rads? If you can't figure it out, be careful as water could get very hot in the heating circuit through cylinder and back to stove. Is there a pressure release safety valve on this circuit? That's what I'd be thinking.

WindWarrior

It's a dormer bungalow. Heat not going to any radiators upstairs or downstairs from the stove. Radiators working okay on oil burner so haven't bled them. When replacing the pump I just closed the valves either side of the pump, replaced pump, opened valves and bleed pump from the bleed point on the pump. I only lit the fire then to test it. There is water in the stove tank in the attic for the stove. could there be an airlock before the pump? But there was water coming out after I bled it. I can turn the pump on and off with the thermostat. Not sure regarding pressure relief circuit. Pipes were making noise the first night I noticed the problem and I ran the hot water to get rid of excess hot water which stopped the banging.

Still stihl waters 3

Probably best to get a competent professional involved

jimf

imho i wouldnt light the stove until you get a competent plumber to check the whole lot out

is that 3/4" pipe i see connected to the stove

maybe 1 of the plumbing lads on here could give their views

how long is the stove fitted

Curious_Case

Is the pump activating when the water from the stove gets sufficiently hot ?

Pipe on far side of pump may get hot (by thermal conduction) in the absence of any water flow.

Hot water tank may not depend on the pump running.

WindWarrior

Stove is fitted 10 years. Pipe is around 28mm coming from the stove to the tank then is stepped down to a smaller pipe

WindWarrior

Pump is coming on from pipe stat from stove

WindWarrior

I have one coming after Christmas but would be nice to get it sorted before then. I will try a few more plumbers tomorrow

Furze99

https://www.boards.ie/discussion/comment/119981764#Comment_119981764

You've a dual system, so a bit more complex and needs a plumber to check in person I'd think. Normally in a solid fuel system, the heated water will rise to upstairs rads without pump, just as it rises to the cylinder and falls back as it returns to stove. Bit suspicious if they're not heating upstairs, is there a valve controlling that circuit.

You can get, probably should have a pressure release fitting on the primary circuit between stove and cylinder. This is for safety in case the water overheats in this circuit for some reason.

WindWarrior

I tried a few plumbers during the week but none available till the new year so yesterday I got a new non return valve and with advice from a plumber drained the system replaced the non return valve, re-pressurised and bled the system. Back boiler now heating the rads so hopefully sorted now. Thanks for all the advice

John.G

A swing check valve should allways be fitted where possible?.

POBox19

https://www.boards.ie/discussion/2058275306/back-boiler-stove-not-heating-radiators

I have a dual oil and back boiler set-up. Seems odd that the oil boiler heats everything but not the stove boiler. Is the stove heat going out to the oil boiler? If it is can you isolate the oil boiler from the system by shutting of the valves into that part of the system, don't forget to set the timer to off. Then see where the heat goes.

notthereyet

Hi wind warrior looks like I have same problem but is oil boiler not circulating heat to rads stove is working OK but never really heats rads. So was thinking of changing circulating pump as pump feels very hot but both pipes are hot coming out so must be working but only heats 2 rads and the rest are cold, my pump is Grundfos 25-80 and looking on line are about the 400 quid all shops are still closed here, is there a cheaper option than Grundfos and what did you pay for yours