Worcester Bosch Heatslave 15/19 Lukewarm Radiators

[sotontotton]

I get the same behaviour so 3 the burner stays on permenantly with only 1 I would say where the burner cuts out and pump stays running..

 

[sotontotton]

I'm back with an update after taking another look today at the boiler.

Decided to drain the system after a flush then to look at the expansion vessel (big red thing on right). Once the system was drained I pressed on the valve on the top of the expansion vessel and rather than 1 bar of pressure coming out I got a wimpy psssffhhh. Disconnected the expansion hose and blew through it then took it off to flush with water. Took the expansion vessel out and this was full of water, maybe 1/2 full so I understand this should have some water in. I emptied as much water as possible from the vessel. I tried to pump up the vessel, but the air came out the connector for the expansion hose. Am I right in thinking the vessel can be pumped up disconnected? I'm thinking the diaphragm is goosed although no water came out the top of the valve.

Refilled everything and put some pressure in the vessel with a pump and now I get instant hot radiators that stay hot rather than lukewarm.

Happy to leave it or buy a new vessel, but just not sure the behaviour of a knackered vessel.

Cheers guys

Chris

 

[oilhead]

A knackered vessel can make you lose pressure from the system, and if this gets too low, then the pump will not have a 'head' to pump round the heating circuit, so ideally it needs to be replaced. The diaphragm is goosed if air passes from the valve to the flexi. You will get some expansion if you have air in the vessel, but this is likely to transfer itself to the main system over time and could cause air locks in the boiler.

 

[sotontotton]

Thanks for the info oilhead.

Plumbarena are doing alright out of me ☺ BTW does the new vessel come charged to 1 bar with nitrogen?

 

[oilhead]

Yes, Precharged.

 

[sotontotton]

Thanks oilhead.

Replaced the vessel and things did improve, but still seem to have water flow through the heatstore/plate exchanger when CH is in demand. Once again pipes either side of the pump are only warm not hot so diverter valve can be ruled out.

Think I have sussed it though looking at the plate exchanger that sits on top of the heatstore. That plate exchanger has a one way valve that I think has turned into two way. This would explain the behaviour I'm getting with CH hot water flowing through the plate exchanger, heat store and related pipework.

I'll update again once fitted. Picture attached is of the plate exchanger that another guy posted when he had a different issue. It shows the check valve.