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[Tug Fanatic]

We have a problem.

Our central heating is water in radiator based. It does not have a header tank but instead runs the system at a slight pressure which you can see via a gauge. There is a manual feed valve to add water if necessary which it has not needed doing in the 15+ years that we have lived here.

A few weeks ago I noticed that when the system switched on first thing in the morning there was a lot of air in the system. I added some water which appeared to stop the problem but it has returned. We now have some radiators that are half full of air.

I suspect a leak somewhere.

The upstairs system is 15mm pipe and there is no sign of any leak although access is, for us, impossible. Certainly nothing has come through the downstairs ceilings.

Downstairs is more complicated. The construction of the floor working up is a concrete base (on which the heating pipes are laid) with wooden "joists" attached to the concrete and insulation between the joists. All this is covered by a plastic sheet and the 22mm flooring chipboard as a floating top surface.

The downstairs pipes are all 8mm or 10mm and all go back. without any joints. to a manifold. The manifold does not have any isolation valves. Other than at the manifold and by the radiators I have absolutely no access. I have managed to get a test prodder all the way to the concrete at both the manifold and all the radiator connections.They are all dry.

I have looked at all radiator and taps. They are all dry.

There is no sign of a leak around the boiler (a Worcester Bosch combi with internal hot water tank) an it does not emit clouds of steam at start up.

Is there anything else that I can test before I call in a plumber. Without enormous disruption I can't see that they can do more than me.

Help please.

[tonyH]

Are the half air rads at he top of the house and did you bleed those rads before you added more water?
I'm not a plumber but sometimes, if the system hasn't been serviced, the chemicals used can break down if oldish.
Good Luck

[Andy M]

Ours cut out due to a pressure drop last week, I opened the valve to let the pressure build back up and it made a gurgling noise, then shut down again. We called out plumber and he took out a small plastic vessel inside the main boiler case, which had a small ball valve in it, he rinsed out some dirt/grit and put it back on and the boiler fired up fine after that. 10 minutes and he was done. Migjt be worth a try?

[Andy M]

Can always blame it on the last plumber if anything goes wrong😁lol.

[Stan]

Hi tug pm sent


Stan

[Tug Fanatic]

Are the half air rads at he top of the house and did you bleed those rads before you added more water?
I'm not a plumber but sometimes, if the system hasn't been serviced, the chemicals used can break down if oldish.
Good Luck

No. Some are upstairs & some down. The bubbling at morning fire up started in the first radiator in the system upstairs but has spread to both upstairs & downstairs. I didn't bleed the system & I am very wary of putting more water into it. My mind sees all this water under the downstairs floor with nowhere to go.
We can often hear the water moving round (small bubbles?) during the day.
Ignoring the half cold / half hot radiators and the bubbling noise the system still functions and we are warm.

[Stan]

I sm waiting for your if you can

[Aerodecked]

I'm not a plumber but I do know that the combi boiler could have an issue with the heat exchanger leaking (some Worcester are prone to it) and this will not present any leak in the house but will go out the "overflow" pipe to the outside world. Check to see if you have any sign of extra water there. It does mean a visit by a heating bod though.

[Perkasaman2]

Switch off your combi. Get a radiator bleed key and bleed each radiator in turn. you will have to top up the pressure system as you carry out the bleed process. When you top up pressure check the pressure gauge on the front of the boiler and continually top up  to 1 bar throughout the radiator bleeding process. If in doubt call out a heating engineer.

[Andy M]

The engineer that came to do ours said that a blocked or frozen overflow could cause the same symptoms as we had, I think he said the little plastic tank was a condensate tank.

[Tug Fanatic]

Hi tug pm sent

Stan

Tank you so much for your help. It clarified a good few things. We are contacting a Worcester Bosch approved engineer after I have has a good look at the overflow (thank you Aerdecked).