NO HEATING DOWNSTAIRS !!

[mmalone]

Quick one guys !!

just been to my old neighbours and heating upstairs works when she puts c/h and h/w demand on....

no downstairs heat at all...

suprima 30 system with mid position valve ... checked the pump and rocked it form 1-3 a few times,,, checked the valve and thought the head may not be powering totally over and pushed it fully across ...

done this and downstairs started to head again,, not sure if its the valve or pump ?

would the valve be at fault for only heat upstairs ?? or is this more likely to be the pump ??

upstairs rad were piping hot and hotwater has been fine...


not 100% on this one as needing to call for h/w to get it to fire suggests the valve head but thought if this was knackered then there would be no heat anywhere...

is it possible the valve aint fully powering therefore pump only strong enough to get round the top rads ??

Oh pump is upstairs also under cylinder !!

 

[ollski]

your going to be looking at the pump to be honest, what sort of pressure does it take to stop it spinning when you press on the end of the impellor?

 

[croydoncorgi]

Sounds like the system has never been properly balanced, so that the upstairs rads are taking all the flow.

Turn down the upstairs lockshields a bit, so that the rads still get enough flow to heat up completely but there's enough pressure to push the hot water downstairs.

Remember that hot water is lighter than cold, so it tends to resist being pushed downstairs, displacing cold water that's sitting in the rads down there! You'll probably find that once the downstairs rads are warmed up, the flow will keep going. But the balancing needs to set up the system for a 'cold start'.

 

[mmalone]

your going to be looking at the pump to be honest, what sort of pressure does it take to stop it spinning when you press on the end of the impellor?

gonna try that tomorrow mate, didnt have time tonight and pump wasnt in a good situation to try.. the pump is my first bet also but just wondered if the mid position valve could cause this also , not done a lot of these but symptons have always been no c/h at all when these need replaced....

 

[mmalone]

Sounds like the system has never been properly balanced, so that the upstairs rads are taking all the flow.

Turn down the upstairs lockshields a bit, so that the rads still get enough flow to heat up completely but there's enough pressure to push the hot water downstairs.

Remember that hot water is lighter than cold, so it tends to resist being pushed downstairs, displacing cold water that's sitting in the rads down there! You'll probably find that once the downstairs rads are warmed up, the flow will keep going. But the balancing needs to set up the system for a 'cold start'.

aint the balancing m8.. the place has run perfectly for 4 1/2 years...

 

[mmalone]

guys heres a bit I forgot to add although may not make much of a difference..

the system has a bypass on it (I know not required on a Y plan )

I was thinking that if the valve failed on c/h then if the bypass is open then this would allow heat to go to the rads but then that had me thinking if this is the case then wouldnt this happen everytime h/w was called for seperately ??

**** it its saturday night and the old screwdriver in the pump will surely show me if thats the problem.. if not I'll remove head and check impellor if these are both sound then move to valve !!


ollski / guys agree with this ?

 

[croydoncorgi]

If the bypass is opened too much, then there will be less pressure to push water through the rads, especially the ones downstairs.

(You never said the system had worked OK 'before'. What was changed?)

 

[meldrew's_mate]

Can you remove the 3 port actuator head? If so do so, and check the valve isn't seized or stiff as this would cause the system to only operate when CH and HW were demanded.
Does the actuator drive fully over when removed, CH and HW are ON, and the HW cylinder stat is turned down?
It could simply be a stiff shaft on a Saturday night, if you push and pull it a bit you may get satisfaction. Better still get a girlie to manipulate it for you while you relax and watch the footie.

 

[mmalone]

If the bypass is opened too much, then there will be less pressure to push water through the rads, especially the ones downstairs.

(You never said the system had worked OK 'before'. What was changed?)

sorry mate nothing has changed, other than it not now working ..

will let you all know how I got on later !!

 

[mmalone]

job done !!!


pump appeared ok,valve body nice and fee.... removed valve head and it didnt fire up boiler or power over when c/h only called for...

can only assume partially opening and small enough resistance to only heat upstairs...

strange as the pump was deffo my first choice here and due to heating upstairs only I didnt think it would be the valve.., may actually be both only time will tell but valve 100% faulty..

 

[croydoncorgi]

Sorry guys,

I don't subscribe to the 'weak pump theory'.

Circulator pumps are universally (more or less) water lubricated synchronous motors, driven by AC mains. Unless the motor coils are partly burned out or shorting internally, the motor can ONLY deliver its rated output(s). The speed adjustment could also be faulty so that maybe setting 3 will give no increase over setting 2, or another easily-detected, similar problem. For a given setting and assuming the coils are OK, the pump speed should stay the same forever.

The other main factor that will affect speed and output is friction in the rotor bearing (ie. it's full of crud and won't spin freely). You can usually easily test this with the pump OFF. If you can't easily spin the rotor using a screwdriver (after removing the large screw in the centre of the pump body) then it's stuffed! (other models with a non-removable plastic finger nut are more difficult to diagnose).

The only other thing that will reduce pump output is air. Water pumps are designed to shift water. With air in the water, the pump will cavitate and output will drop A LOT. But if there's air in the system, the first task is to get rid of it anyway.

 

[wilhelminajmd]

Hi,

I think that I've got a related problem to this. Lived at my house for 7 and a half years, and the heating has always worked fine. Over the last couple of weeks the radiators downstairs have stopped working. Upstairs rads are nice and hot, and hot water is functioning normally.

Last night I turned off all of the upstairs radiators, and all bar one of the downstairs - and the downstairs one that was left on heated up nicely. When I turned on another one downstairs, it heated up, but the original one that I had put on went cold.

I don't know what I'm looking for with the pump, so I haven't been able to check this. Is there a simple of way of checking for air blocks, or does this look like I'll need to get a professional in??

Thanks in advance,

Wilhelmina