Hot water but only one radiator working,HELP.


Postby armytouch » Thu May 08, 2008 1:33 pm

Hi have just moved into house and things seemed fine until i went to plumb in my washer,no pipes so called in plumber. He turned off heating and cold water,he then went to find water tank which had been moved into attic he explained that when the cistern had been moved no stop valves had been installed either to the cistern or to the water supply,the only stop valve was the cold water stop cock,so he would have to drain the full system so could put in the hot water pipework for the washer.
He ran off all the water and installed the washer taps,he then refilled the system bled the radiators relite the pilot like and put heating on.The hot water was fine and the radiators warmed up so he left.
The radiators installed upstairs are different than down,upstairs have only one valve on one side and then pipe runs straight out without valve the other side,where as radiators downstairs have valves both sides.
The next day only one of the radiators would come on,hot water fine,it was the upstairs bathroom radiator both side pipes going in and out were hot but all others where cold, i was told to check the pump which is a very old one,it was hot and pipes on either side where hot,however the pipe running to the next radiator approx 12 in from the pump was getting cold.
I looked at radiator and there is a drain valve between the pump and the radiator thought releasing valve may release air lock however when opened it nothing was released no air and only tiny drops of water,so undid the radiator side valve along from drain valve and water was released.
Have tried to give as much information as possible,if require more please ask.
I would like some advice on what as caused this problem and how it can be fixed,is it an air blockage,if so how can i rectify it,is it the pump gone,how can i check to see if pump working correctly,why is pipes hot going into pump,pump hot itself and pipes hot coming out for about 12in before it goes cold.
Any help and advice would be very grateful
all the best
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Postby ericmark » Sat May 10, 2008 6:29 am

One thing does not make sense. The central heating water is nothing to do with domestic hot water so even if he did have to drain off domestic hot water it should not affect central heating.
As to central heating there are many systems open and closed W, Y, S and C plus combi boilers with or without valves and with all pumped or just central heating pumped. Megaflow storage tanks and normal copper cylinders. We need to have an idea of what you have.
I keep looking at bleed radiators which does not make sense! I can not think of any reason to drain down central heating to fit washing machine.
I am an electrician maybe a Plumber will have something I have missed but as electricians we need to understand central heating in order to wire correctly and the only thing I can think of is plumber drained from storage tank and made a mistake between being open or closed vented and drained wrong side. In most systems tank is domestic water and coil in tank is central heating but some newer types are other way around and you have mains pressure hot water.
But I would just get him back to fix it anyway.
ericmark

Postby rosebery » Sat May 10, 2008 7:17 am

Well perhaps I'm being thick today but this don't make sense to me either! I can think of no reason whwy the CH would need to be drained. Yes perhaps he did need to empty the CW Storage tank in the roofspace. Is there a second, smaller, tank up there as well?

Yes please give more detail as to the configuration of your system.

Did he suggest fitting appropriate valves when he had it drained? No, I suspected not.

From what you say it does sound like you have some air in the system but the drain cock is not the place to get it out.

Your plumber needs to be called back. I agree with ericmark.

Cheers
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Postby htg engineer » Sat May 10, 2008 9:09 am

Basically the problem only occurred because the plumber drained the heating system when there was no need to (if the info you're giving is correct).

Therefore it is his fault and he should put it right, get him back to fill and vent system. Clear any airlocks and get the heating working again.
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Postby armytouch » Sat May 10, 2008 9:46 am

Hi,have checked in loft and its a copper cylinder system,the plumber was right there are no stop valves at all on any pipework and he did say it best to get them fitted, there is one radiator drainoff plug and water stopcock,a very old pump.Think its a back boiler,but not one stop valve apart from mains stopcock.
When plumber drained system he just turned off water stopcock and ran hot and cold water off through taps,then fitted plumbing for washer, didnt drain off the radiators. Why is the hot water going into pump hot then out pump hot but going cold about 12 in from pump?any idea why the radiator drainoff not draining when opened? can i check to see if pump working,have felt it and it hot between pipes but cant feel any vibration or sound from it ?
where and how would the air block be cleared from the heating system ?
I rang the plumber and he said he didnt drain heating system he just ran off cold and hot water.


Thanks for your advice keep it coming.
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Postby htg engineer » Sun May 11, 2008 9:17 am

Unscrew the vent point on the pump, you should be able to tell if the pump is running or if is stuck.

The drain off on the radiator may be full of debri or the rubber washer may have came off and this is blocking the water from coming out, if he didn't drain the system the radiators should still be full.

Heat will rise so you weill get heat from upstairs radiators, also it is possible the bathroom radiator could be plumbed into the primaries, some peopl do this.

It sound like it's the pump at fault, as you say you can hear a vibration there must be power to the pump. It's probably stuck.
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Postby armytouch » Sun May 11, 2008 11:06 am

Hi again,
The radiator in the bathroom was working but only heated up half way so the plumber bled it and it working fine, i cant hear or feel any vibration from the pump,so if it wasnt working would it still allow hot water to pass through it,you mentioned a vent valve where would i find it and whats it look like and how would i release an air blockage in the system?
thanks
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Postby armytouch » Wed May 14, 2008 6:48 pm

Hi, hot water going into pump, pump hot and water hot coming out of pump but then goes cold about 6in from pump, all radiators cold apart from one upstairs. It is a very old pump i cant hear anything or feel any vibration from pump, could it be the pump causing the radiators not to heat up, is there anyway i can check the pump to see if working?
thanks
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Postby htg engineer » Thu May 15, 2008 3:27 pm

"Unscrew the vent point on the pump, you should be able to tell if the pump is running or if is stuck"

The pump will normally have a vent, either a silver screw head undo insert screwdriver slightly and you'll feel/hear if the impeller is turning.
or
a black plastic hexagonal nut, unscrew and press again you will hear/feel if it is working.

If you don't think it's working, a couple of sharp knocks on the pump body may get it going - but in the long term i'd look at renewing the pump, to prevent the same happening when the weather is not so good.

htg
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