This is a bit long, sorry....
An acquaintance has a heating problem. For complicated reasons, I'm in char ge of sorting it out, at least for the next few days.
It's a y-plan system with an Ideal Mexico Super 3 boiler. The boiler is at least generating heat. It's been messed about with by a large contractor X , and for safety it seems one should assume they've broken everything they' ve touched. In particular, I know they replaced the ballcock on the heating header a few weeks back, and replaced some rotten overflow pipe (but not a ll of it!). I also know that they recently replaced the 3-way valve, and p ower flushed the system. They are now recommending that the landlord strip out the existing boiler/cylinder and replace with a combi. For £6K. I told you they were a large contractor....
It's leaking warm water from a pipe outside the building. All indications p oint to this being the heading header tank overflow.
The cylinder stat is not actually measuring the temperature of anything exc ept a random piece of air. I've attempted to duct-tape it to the cylinder, though I don't expect that to last long. The tenant has been using the imme rsion heater, so the water is rather hot!
I orginally thought that the leak was due to overheating, but after I disco vered that X had replaced the ballvalve, it seem more likely that they had n't set it properly. I had a look at it the previous night, but was in a ra ther precarious position standing on dodgy carpentry...
Apart from the leak, the real problem is that the radiators are not getting hot (except the first one on the circuit). I'm not that familiar with 3-wa y valves - I presume that it's a mid-position valve rather than diverter (i t was recently replaced by X) but I don't know.
When I arrived, the first rad was cold. I turned off the HW, and left CH on continuous, and the first rad warmed up - but no others. I presume that th is indicates at least some flow, but possibly minimal. I don't *think* it i s heating up just on conductance through the pipes.
I have searched in vain for any bypass which might have been fully opened ( and in any case I'd then expect the return to be hot, and if I'm correctly identifying it, it isn't).. All I can think of is an airlock. I bled all up stairs rads and got nothing but water. I verified that the pump valves were open. Lots of heat seems to be going up the pipe to the header tank, which again (I think) suggests mimimal flow on the rad circuit.
It seems to me that I ought to go back and ensure the ball valve is set pro perly, and probably replace the cylinder stat. That, however, is secondary to the heating problem, and while those two things will stop fresh water en tering the system, they won't fix any existing blockage.
The only possibility I can think of is to whack the pump up to max and clos e the first rad, and see what happens. Any other suggestions welcome! Obvio usly there is the possibility that the valve isn't opening properly, though I'm not clear how I can test that.
I've got a plumber who ought to be competent coming round on Sunday (I hope ), but if I can get them -and their young kids - some heat earlier, we woul d all be happier.