stupid new problem - blocked cold feed?

[FrancesDoesItHerself]

Hello again

I decided that the previous problem with my system had to be the pump (see my previous post 3 upstairs radiators working, the rest are cold) - replaced it eventually with much swearing! I had to drain the system to do it 'cos the gate valves were stuck.

Now when I try to refill the system there is nothing, no water in any of the radiators or pump, and a trickle comes out of the drain valve. The header tank is full and the ballcock is working, the pipe leading out of it doesn't seem to be blocked.

Does this mean my cold feed is blocked? And if so, what do I do about it? I can't see where the pipe from the tank goes to, it goes through the attic floor and I presume down to the boiler in the kitchen but it's all boxed in so I can't see what is going on. The pump is in the airing cupboard upstairs, has no water reaching it.

(As a recap, I have a non-combi boiler, fully pumped hot water and ch system, my downstairs radiators weren't working so I replaced the pump).

My house has been cold for three weeks now, I still can't get anyone to come out and sort it out and I am getting really fed up!

Please help

Frances

 

[oilman]

Cold feed blocked? Yes. you will need to cut the pipe to clear it (probably) so you need to find where it joins the circulation pipes.

Which part of the country do you live in?

 

[FrancesDoesItHerself]

I live in Hull.

I have pulled part of my kitchen apart to get at the pipes but they just disappear behind the boiler, I can't see what is going on. There are four pipes in two sets of two if you see what I mean. One of them is lagged.

Frances

 

[DP]

Locate the lower connection on the cylinder that is connected to boiler pipes. This will rise to the F&E cistern in the loft. It will be 15mm. Remove tee that connects boiler return, feed from cistern and return from cylinder. and clear same. Be prepared to get wet.

 

[FrancesDoesItHerself]

Any idea where the tee is likely to be? I can't find it.

Frances

 

[CH4]

Frances,

There may be an air lock in the cold feed that is preventing the system from filling. One way of overcoming this is to slowly refill the system, via the drain valve, using a garden hose connected to a tap (at mains water pressure). Close the downstairs radiator air vents as water emerges, then do the same for the upstairs radiators and any high point vents. Shut off the water when the level in the header tank starts to rise, and close the drain valve.

IMPORTANT! Remember to vent the pump before switching the system on.

 

[oilman]

Sorry to be picky DP, but though you may be correct about the pipe layout, there are so many non-standard systems about that it's unlikely the pipes will run where you think.

The possibility of an airlock is much less than the possibility of a blockage, and if you fill the system from the bottom, it will disguise the problem of the blockage. If it IS an airlock the pipes should be sorted so you get rid of the problem, rather than cover it up 'til next time (when you will have forgotten everything and have to post another message).

 

[CH4]

The possibility of an airlock is much less than the possibility of a blockage, and if you fill the system from the bottom, it will disguise the problem of the blockage.

I agree. Nevertheless, if while back filling the system water enters the header tank via the expansion pipe, then a blockage in the cold feed will be confirmed. In which case, temporarily capping the expansion pipe (with a push fit stopend) may allow the blockage to be flushed with mains water pressure alone.

If it IS an airlock the pipes should be sorted so you get rid of the problem, rather than cover it up 'til next time ...

I again agree, but this could be done when the heating season is over.

 

[DP]

The only way to find out is dismantle (with care ) a fitting that is in the pipe through which the system water expands when system is running. It is not the vent pipe but the feed pipe which the original poster indicated, is not 'drinking' water but the system is empty.

Back fill will no doubt introduce water into the system via the vent pipe, it will not clear a blocked feed pipe. I know, I tried it. With mains pressure on the vent pipe (hoping water would be expelled up the feed pipe) pressure blew the overpressure (spring loaded) vent. If blocked feed is not cleared, imagine what will happen if boilerstat was to fail- boiler would run dry.