Back boiler producing lovely hot rads - but tepid 'hot' water.

Investigated the airing cupboard: The hot pipe comes in from the boiler to a 1970s white plastic 3 way manual valve - marked with a red&green spiral design and the text 'Hot Water' - 'Radiators'. This is siezed in the mid setting and hasn't been budged for years.

The CH pipe comes out of this valve hot, whereas the 'hot' water tank coil pipe comes out of this medium hot, then turns 90degrees (to go up to the hot tank) after the 90degree turn the pipe is lukewarm.

Is this a 'blockage' problem?
Would flushing solve it - or potentially make it worse?
Are replacements available for a 3-way valve?
How much would be a fair charge to remove valve, clean, fix replacement/refurbished valve ?

Not sure if I've forgotten anything......

BigDave, January 2009

Top advice Tony.

Its working now! I think your air lock diagnosis was spot on.

Solution:
Last night I took off the rad nearest the boiler, flushed the rad (no actual 'sludge', more the consistency of ink), also drained a tiny bit of water (it was very clean)out of the system via the In rad valve.
Then replaced the rad, fully opened all rads, turned the old faithful baxi bermuda 551 back on at medium temp, balanced all the rads in the property. Hey presto.

Don't know whether it was air (would make sense as the DHW inlet into the hot water tank is the 2nd highest point after the filler tank). But the system seems to be circulating well now.

Cheers,

PS, Have another one;
Since all this activity, the analogue timer switch (very simple, with 2 time slots on a 24hr revolving dial on the front, plus a Timer/Off/Constant toggle switch on the side) has given up the ghost. What would be a fair price for fitting a new one ?

BigDave47, January 2009

Top advice Tony.

Its working now! I think your air lock diagnosis was spot on.

Solution:
Last night I took off the rad nearest the boiler, flushed the rad (no actual 'sludge', more the consistency of ink), also drained a tiny bit of water (it was very clean)out of the system via the In rad valve.
Then replaced the rad, fully opened all rads, turned the old faithful baxi bermuda 551 back on at medium temp, balanced all the rads in the property. Hey presto.

Don't know whether it was air (would make sense as the DHW inlet into the hot water tank is the 2nd highest point after the filler tank). But the system seems to be circulating well now.

Cheers,

PS, Have another one;
Since all this activity, the analogue timer switch (very simple, with 2 time slots on a 24hr revolving dial on the front, plus a Timer/Off/Constant toggle switch on the side) has given up the ghost. What would be a fair price for fitting a new one ?

BigDave47, January 2009

yeh Dave it will be an air lock.Bang it on Water only and crank the boiler stat to high and leave it for a while.It may bang and clout,but should push the air lock out the way.You can then turn it back down to your desired setting.Hope it works for you.

Tony S, January 2009

Thanks for your help Tony.

HW pipe leading to the tank coil is now hot after the manual-3-way-valve, but I'm still getting only luke warm water.

By the way, should ave said this all started happening after the system went a bit dry after the filler tank failed to top-up.

Could it be an air lock ? If so how can it be cleared ?

BigDave47, January 2009

Thanks for your help Tony.

(the manual-3-way-valve has 'Simplicity' stamped on it.)

HW pipe leading to the tank coil is now hot after the manual-3-way-valve, but I'm still getting only luke warm water.

By the way, should ave said this all started happening after the system went a bit dry after the filler tank failed to top-up.

Could it be an air lock ? If so how can it be cleared ?

BigDave47, January 2009

These valves were a cheapo version of a motorised valve but they always seemed to seize up.Chances are is that the DHW side is virtually closed hence tepid water.Im not sure if you can still get them.You are always tempted to give it a crack with a hammer to try and move the lever but you know what water is like.You may need to drain the system but just enough so you can take the whole valve off.You will be able to see the problem then and if need be take it to your nearest plumb center to see if they sell anything similar.

Tony S, January 2009