Anybody good with central heating????

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Heavy Breather

Heavy Breather

Well-Known Member
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Bolton boy living in salford
HELP!!!!! I over pressurised the central heating yesterday, it did a bit of banging and clunking and emptied itself, fine i thought its chucking out the surplus water! Now when i switch it off all the pressure drops, its fine while its running, i've bled the rads and they're all hot. I have to repressurise the system when its been turned off for about 25 mins, i have no idea where the water is going, the overflow is dry, i've checked under the floor, i thought perhaps a pipe had blown off with the pressure but its bone dry. Any help would be great:mad:
 
Heavy Breather said:
HELP!!!!! I over pressurised the central heating yesterday, it did a bit of banging and clunking and emptied itself, fine i thought its chucking out the surplus water! Now when i switch it off all the pressure drops, its fine while its running, i've bled the rads and they're all hot. I have to repressurise the system when its been turned off for about 25 mins, i have no idea where the water is going, the overflow is dry, i've checked under the floor, i thought perhaps a pipe had blown off with the pressure but its bone dry. Any help would be great:mad:
Click to expand...

what sort of boiler is it and do you have expansion tanks in the loft (a seemingly empty tank in the loft with a 22mm copper pipe aiming into the top of it ) if so this is where the water could be going as the top safety valve could be stuck open

and if theres a pressure gauge on yer boiler for the central heating it should be at 1 to 1.5 bar normal operating pressure 3 or above is what the main safety purge valve opens at and causes the clunking noise as its banging shut and being reopened by the pressure
 
Heavy Breather said:
HELP!!!!! I over pressurised the central heating yesterday, it did a bit of banging and clunking and emptied itself, fine i thought its chucking out the surplus water! Now when i switch it off all the pressure drops, its fine while its running, i've bled the rads and they're all hot. I have to repressurise the system when its been turned off for about 25 mins, i have no idea where the water is going, the overflow is dry, i've checked under the floor, i thought perhaps a pipe had blown off with the pressure but its bone dry. Any help would be great:mad:
Click to expand...

Assuming its a condensing boiler and a pressurised system you have 3 "overflow" pipes which could be anywhere. My systems in the garage and only 2 exit outside. The 3rd ****es on the floor, but yours may be hidden.

1. The condensate drain

2. The overflow.

3. The pressure relief dump.

Of course your system could be entirely different.
 
I pressurise it up to 1 bar, switch it on and it increases to 1.5, switch it off and it drops to nil.
Its a condeser boiler, 2 drain pipes outside which are dry not sure of a 3rd, there is a valve on the inside of the boiler that i've used to drain the system.
The floor is bone dry everywhere.
 
Heavy Breather said:
I pressurise it up to 1 bar, switch it on and it increases to 1.5, switch it off and it drops to nil.
Its a condeser boiler, 2 drain pipes outside which are dry not sure of a 3rd, there is a valve on the inside of the boiler that i've used to drain the system.
The floor is bone dry everywhere.
Click to expand...

Sounds similar to mine. When the boiler is working one pipe at least should have a few drips of condensate. The pressure relief valve should drain externally as well but a lot dont if fitted in garage, just ****es onto floor.

Unless I'm mistaken you cant lose pressure without losing water. Sounds very odd.
 
The pressure is now up to 2bar, thats its max, rads are all fine, but if i turn it off the pressure drops to nil in about 25 mins and then i have to fill it up. But where is the water going? Could it be an airlock?
 
Heavy Breather said:
The pressure is now up to 2bar, thats its max, rads are all fine, but if i turn it off the pressure drops to nil in about 25 mins and then i have to fill it up. But where is the water going? Could it be an airlock?
Click to expand...

Its a possibility tho' it would be a significant one. Have you bled all radiators starting furthest from boiler back?

Is it individual micro bore pipework from the boiler by the way? The total water volume is not as much as you might think and a small leak might be the problem.
 
Heavy Breather said:
I pressurise it up to 1 bar, switch it on and it increases to 1.5, switch it off and it drops to nil.
Its a condeser boiler, 2 drain pipes outside which are dry not sure of a 3rd, there is a valve on the inside of the boiler that i've used to drain the system.
The floor is bone dry everywhere.
Click to expand...

The water is definitely going somewhere - do you have a floating [sic] floor - could it be emptying into a void under the boiler?

You need to bleed the rads from the top one furthest away first (while someone else mans the filler valve). - could it just be that they aren't full yet? It always takes a surprising amount to fill them!
 
Bonkers said:
Its a possibility tho' it would be a significant one. Have you bled all radiators starting furthest from boiler back?

Is it individual micro bore pipework from the boiler by the way? The total water volume is not as much as you might think and a small leak might be the problem.
Click to expand...

Yeh its 10mm but i can't find anything wet at all, its been like this since i over pressurised it yesterday, bled all the rads, little bit of air in one but that was all
:confused:
 
Oddie said:
The water is definitely going somewhere - do you have a floating [sic] floor - could it be emptying into a void under the boiler?

You need to bleed the rads from the top one furthest away first (while someone else mans the filler valve). - could it just be that they aren't full yet? It always takes a surprising amount to fill them!
Click to expand...

I've checked under the floor, i've checked the over flow with the boiler switched on and off. The pressure doesn't drop while its on but as soon as its switched off you can see the gauge dropping:(
 
Hard to say without sight of the system.

The pressure relief valve should vent thru a pipe to outside as it can contain water.

Whether you have a pipe or not, you will have a valve.

Might be its faulty and venting air pressure and not water, as you keep topping it up. i.e if you left it longer water would dribble out.

In this weather you dont want to leave it long to find out so you might have to keep topping up then when it gets warmer see if leaving it longer results in water from the valve.

In the meantime keep an eye out for water!
 
Heavy Breather said:
I've checked under the floor, i've checked the over flow with the boiler switched on and off. The pressure doesn't drop while its on but as soon as its switched off you can see the gauge dropping:(
Click to expand...

I think you still have air in the system then. Get someone at the tap to keep the pressure between 1 and a third and 1 and a half bar while you go round bleeding all the rads, starting with the one at the end of the line. Water's either escaping or it's filling the things up! These things don't drain without you knowing about it!
 
What make and model is it?

I take it, it's a combi boiler? ie, direct hot water and no header tank?
 
Oddie said:
I think you still have air in the system then. Get someone at the tap to keep the pressure between 1 and a third and 1 and a half bar while you go round bleeding all the rads, starting with the one at the end of the line. Water's either escaping or it's filling the things up! These things don't drain without you knowing about it!
Click to expand...

Yep, sums up what I meant.
 
Heavy Breather said:
HELP!!!!! I over pressurised the central heating yesterday, it did a bit of banging and clunking and emptied itself, fine i thought its chucking out the surplus water! Now when i switch it off all the pressure drops
Click to expand...

Without actually seeing the boiler, this is just a guess but here's my theory.

Based on the above quote - You did something to a previously working boiler and now it no longer works as before. Unfortunately, it's wishful thinking that it could be as simple as an air lock.

My guess is that you have a leak. A pressure relief valve opening is not going to cause an air lock. You've tested the rads and they are all hot so that would also eliminate that issue.

Seem that you've either blown a joint or the PRV hasn't closed properly.

Try putting a jam jar under the PRV outlet and see if you get any water. You should get none, even the slightest drop will cause a drop in pressure. Especially on a microbore system.

The only other thing you can try is to isolate parts of your system - try turning off all the rads, pressurize the system and see if that helps. If it does you can eliminate each rad one by one. If it doesn't and you get no water in the jam jar it's time to get the floor up.
 
milonic said:
Without actually seeing the boiler, this is just a guess but here's my theory.

Based on the above quote - You did something to a previously working boiler and now it no longer works as before. Unfortunately, it's wishful thinking that it could be as simple as an air lock.

My guess is that you have a leak. A pressure relief valve opening is not going to cause an air lock. You've tested the rads and they are all hot so that would also eliminate that issue.

Seem that you've either blown a joint or the PRV hasn't closed properly.

Try putting a jam jar under the PRV outlet and see if you get any water. You should get none, even the slightest drop will cause a drop in pressure. Especially on a microbore system.

The only other thing you can try is to isolate parts of your system - try turning off all the rads, pressurize the system and see if that helps. If it does you can eliminate each rad one by one. If it doesn't and you get no water in the jam jar it's time to get the floor up.
Click to expand...


I'm working this weekend so i'll have to do it monday, still can't find any leaks but i'll try draining and repressurising it see if that cures it.
i'll let you know what happens.
Thanks
 
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