No hot water after bleeding CH pump

[spooky_b329]

Following on from yesterdays thread...//www.diynot.com/forums/viewtopic.php?t=108402&postdays=0&postorder=asc&start=0...as you'll read I've successfully bled my CH pump and radiators now get nice 'n hot...thanks Hi-Spec.

However I now don't have any hot water at my taps. The boiler will fire up but after a minute or two it shuts down, with no heat in the pipes around the cylinder. The pipe that passes through the CH pump in the boiler gets hot until it disappears under the floor, and a pipe I assume is the hot feed to the cylinder is hot where it exits the boiler but is cold where it begins its ascent to the cylinder.

Its a 15yr old boiler, with a vented CH system. I'm not familiar with how these things are plumbed so not sure if it could be related to air in my CH system or a 3 way valve is stuck. (Don't even know if I have one...if there is then its below the floorboards...

Thanks for any help.

 

[hi-spec plumbing heating]

you had a motorized valve next to the cylinder that i see in your pic yesterday.

 

[spooky_b329]

I've just come back from taking another look at that

So as it has a single pipe passing though I'm guessing I have a 2 port valve...is this possible as the sticky thread suggests I should have either a single 3 way or two 2 ways.

I'm assuming if I move the lever to Manual I'll get hot water when the controls are set to either Hot water only or HW and CH? Once this valve sticks can it be fixed or is it replacement only?

 

[hi-spec plumbing heating]

i wouldn't of said it stuck as it worked before you drained system.
when the system calling for hw is lever free or has it got tension on it when you move it.

 

[spooky_b329]

It might not have been working...we moved in 9 months ago, we stuck the heating on for 5 minutes and once I felt heat at the rads I turned it off. Not been used since as we've had a couple of rads temporarily removed since the summer.

Will fire the thing up and see if the lever has tension on it.

 

[spooky_b329]

OK, controls have been calling for Hot Water since I started the thread, and the lever was moving freely. I just turned the controls off, and now the lever has a motor holding it in 'Auto'. Pushing it part way to manual results in the motor pushing it back.

 

[hi-spec plumbing heating]

it's working
i would say you have another airlock in that section looking at the pipework.
pushthe lever right across it should slot in a groove and hold there.

with out boiler on
the air may free its self

 

[spooky_b329]

How long should I expect to leave the lever in manual? I left it for a few minutes then let it return to auto and fired up the boiler but there was no change, so have switched it off and put lever back in manual...

 

[hi-spec plumbing heating]

can you get to the nut on the back of the valve and do the same as yesterday bleed the pipe.
but put lever in auto so valve is shut.

i would say you have air trapped in that section of pipe to cylinder.

is any of the pipe from floor to the valve warm ?

 

[spooky_b329]

None of the pipe is warm except the first section by the boiler. I was thinking an airlock would be unlikely as the pipe passes from downstairs boiler, straight through airing cupboard and into the loft. The motorised valve is within a few inches of this pipe so I would have thought any air would have continued upwards instead of following the Tee'd off pipe. Also there ain't much space to swing a wrench as the valve is partway behind the boiler!

 

[spooky_b329]

Could it be possible that I have an airlock within the boiler itself?

 

[hi-spec plumbing heating]

i agree.
but you drained system so your coil in tank would of emptyed the when you refilled the valve was shut which would of caused air to trap.

but boiler is running ok on heating mode.

 

[hi-spec plumbing heating]

by the sounds of it your hw is gravity fed not pumped

 

[spooky_b329]

Yes, no sign of a second pump. About to try and bleed air at the valve.

 

[hi-spec plumbing heating]

ok