Hi I hope someone can help me – it’s getting beyond a joke….
My house, built in 1963, has a single pipe system.
4 years ago my ex –husband built on an extension and put a ring of radiators in and connected them up – however the ring he created is 2 pipe and he connected it into the hot water supply!!!
4 years have gone by and the heating in both parts has worked fine…. Good and hot.
This winter the main part of the house stopped, the 2 pipe carried on (with a slight noticeable decrease in hot water available)
When we isolated the 2 pipe system the main house came back on again fine.
We changed the pump – no difference, we changed the valve, no difference.
We got a plumber in to look – we told him about the strange arrangement above (that we’d only just found out about whilst investigating) – first he blamed the boiler so that was checked – no problem / no difference. He replaced the valve (yep again) no difference, he checked the pump. He emptied and re-filled system (showing there was no gunk in the system), no difference.
He re- piped the 2 pipe into the single pipe system (though he didn’t do it near or off a manifold – I’ve just read that in here somewhere and that was never mentioned) – now the whole system doesn’t work. Isolate the 2 pipe system and still no heat.
The boiler comes on – stops on for about a minute and half, bangs very badly and turns itself off – plumber tells me that’s because the water it is heating is so hot / not going anywhere.
We’ve checked the spec of the boiler and it is capable of a lot more than the system we have.
The plumber has condemned the system saying it needs completely replacing.
We’re sure that’s not the case because under certain circumstances (isolating the 2 pipe section) it worked fine.
Has anyone got any ideas? All we want is to get this working again with a view to replacing in the future.
If your post had stopped at the fourth paragraph I would have suggested the motorised valve. From your seventh paragraph I would still suspect the MV and that it has been wired wrongly.
The situation you are now in is so complex that I doubt whether you will get a solution from remote advice.
Your plumber has messed about with the system so much that your chances of returning it to its original working condition are remote.
You can either continue with the same plumber or start again with a different one.
'The boiler comes on – stops on for about a minute and half, bangs very badly and turns itself off – plumber tells me that’s because the water it is heating is so hot / not going anywhere.'
He's right in a way, if the boiler is banging then cutting off, the boiler is overheating because the heat isn't getting away from the boiler. At any point during all this draining, altering pipework and refilling was the system flushed and had inhibitor added - I'm guessing probably not. So it could be the boiler heat-ex and pipework is full of limescale, flux etc
You haven't mentioned the boiler make and model, on some boilers they wont come on until the pump has proved itself, on older boiler the boiler will run whether the pump runs or not, and will cause the problmes you describe, check the pump, just because it's been changed once - doesn't mean it's not the fault, also vent pump.
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