Help - no hot flow upstairs

[roxburd]

Hi all,

Need some help from someone who actually understands the black magic that is plumbing!

I just replaced the hot water down service stop cock/gate/tap thing - it's just above the hot water tank on the first floor. Everything seemed to be going so well. Now we have everything working fine except the upstairs hot - it will run for a little while (10 secs or so) then the flow slows to a very slow flow. Five minutes later it will flow again and then slow again.

The cold is fine all round the house and the hot flow is fine downstairs.

I ran the boiler to heat the water for a few minutes but turned it off when I realised there was a problem as I was concerned there could be an airlock or something and running the boiler with the system like that could cause damage.

If I put a loopback on the kitchen tap (ground floor), feeding cold mains back into the hot circuit the flow rate improves upstairs but there's no gurgling or spluttering.

The system has regular hot tank on the first floor, boiler on the ground floor.

Cheers!
Dave

 

[terryplumb]

Hi Dave ,sounds like you may have an airlock ,but can you confirm a few things . do you have loft tank feeding a vented hot water cylinder and the valve you replaced is it on the cold feed to the hot water cylinder ( this goes from the loft tank to the bottom of the cylinder ) and finally is the valve a gate valve ( big round ,red wheel on it ) ?

 

[roxburd]

Hi Dave ,sounds like you may have an airlock ,but can you confirm a few things . do you have loft tank feeding a vented hot water cylinder and the valve you replaced is it on the cold feed to the hot water cylinder ( this goes from the loft tank to the bottom of the cylinder ) and finally is the valve a gate valve ( big round ,red wheel on it ) ?

Thanks Terry, that was quick!!!

loft tank, yes
feeding vented hot water cylinder, yes
yes, replaced 22mm gate valve feeding cold to the hot water cylinder.

Anyhow, I read back my post after I'd hit 'submit' and thought "Well, why not try doing a loopback upstairs too?"

The system did three MASSIVE belches (via the hot overflow into the loft tank, I think) and the system's all now flowing just fine!!

Thanks for the reply, Terry. It just needed burping from the right spot!

Well, I still have to check the hot water heats and the shower gets hot water (that's why I was doing the job in the first place - to replace the 22mm gate controlling hot water to the show as it had failed shut).

I replaced the two failed Italian-made gate valves with British Standard approved Pegler units (£15 instead of £6 for the Italian-style ones) - hope they are better quality!

Cheers Terry,
Dave

 

[terryplumb]

Glad your sorted .I hate gate valves no matter who makes them ,pegler are probably the better though , they tend to seize up ,won't close fully and if they shear ,don't open. Full bore lever operated are miles better if you ever need to replace another gate valve. Regards terry.

 

[roxburd]

Glad your sorted .I hate gate valves no matter who makes them ,pegler are probably the better though , they tend to seize up ,won't close fully and if they shear ,don't open. Full bore lever operated are miles better if you ever need to replace another gate valve. Regards terry.

Oh my god, I looked at those and thought they'd be better - only used gate valves because I thought I'd better replace like with like.

Ah well, full-bore lever-operated ball valve next time then!

 

[roxburd]

Glad your sorted .I hate gate valves no matter who makes them ,pegler are probably the better though , they tend to seize up ,won't close fully and if they shear ,don't open. Full bore lever operated are miles better if you ever need to replace another gate valve. Regards terry.

My cold water down service gate valve was seized open and my shower hot water feed gate valve was seized closed!

 

[terryplumb]

There you go ,told ya !!