Boiler constantly losing pressure.

  • Thread starter Thread starter Dougie1702
  • Start date Start date
Woke up this morning and pressure was absolutely dead zero. This means it's the boiler yeah? So I can tell the gas engineer thats coming out to fit a new pump etc, that I have done this test and it will hopefully direct his attention to the boiler and not pulling up my floorboards?
 
If the isolation valves were fully closed I'd be looking at the heat exchanger.
If the water was coming from the prv pipe you would have noticed that and you've previously stated the boiler insides are dry.

Get the gas engineer to carry out the same isolation test if he doesn't believe your conclusions.
 
Mike83 said:
If the isolation valves were fully closed I'd be looking at the heat exchanger.
If the water was coming from the prv pipe you would have noticed that and you've previously stated the boiler insides are dry.

Get the gas engineer to carry out the same isolation test if he doesn't believe your conclusions.
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Boiler insides are dry yes. I noticed that with the isolation valves closed this morning, the dial wasn't just reading in the zero region, it was lower than the zero region, like it had completely emptied itself.
I have tied a bag round the PRV overflow that is situated on the outside wall, it is bone dry.
 
The white pipe at the far right. Pull this down about an inch. This will then let us see if water is coming from the heat exchanger.
Obviously top up the pressure and don't use the heating or hot water.
 
Dougie1702 said:
Woke up this morning and pressure was absolutely dead zero. This means it's the boiler yeah? So I can tell the gas engineer thats coming out to fit a new pump etc, that I have done this test and it will hopefully direct his attention to the boiler and not pulling up my floorboards?
Click to expand...
Sounds like the first line of a classic R&B riff. You appear to have covered all the bases, I'm stumped.
 
Hmm. Interesting reading.

I don't know, I was just thinking... if heat exchanger is leaking, shouldn't be there some water inside and under the boiler?

That water must end somewhere, right?

So I was thinking further... IMO, the only place where you don't realize any leak is your tap. Isn't it possible that diverter valve failed ( in the very strange way ) and it diverts small amount of CH water to DHW system...?
 
The boiler pressure went through the roof last night. Into the red and opened the PRV. The pressure vessel was just charged though so any other reason for this?
 
Tom ,if heat ex is leaking the water is evacuated with the condensate from the boiler ,so you wouldn't notice as the condensate pipework is always dripping , whilst boiler is on. Regards terry.
 
Dougie1702 said:
The boiler pressure went through the roof last night. Into the red and opened the PRV. The pressure vessel was just charged though so any other reason for this?
Click to expand...
Did you over pressurise the system yesterday. Or maybe not fully closed the filling loop ?
 
No, it's at a normal pressure then once the heatings been on for 10 mins, it's at nearly maximum pressure (in the red)
 
Check all valves that you have been working on are fully open ,except filling loop which should be fully closed. Otherwise it points to a problem with EV .
 
EV? Expansion vessel? That was just charged etc with the proper air the other day... How does this fail? Split diaphragm?
 
Tom86 said:
Hmm. Interesting reading.

I don't know, I was just thinking... if heat exchanger is leaking, shouldn't be there some water inside and under the boiler?

That water must end somewhere, right?

So I was thinking further... IMO, the only place where you don't realize any leak is your tap. Isn't it possible that diverter valve failed ( in the very strange way ) and it diverts small amount of CH water to DHW system...?
Click to expand...
Or the secondary heat exchanger leaking?
 
The boiler was always looked at by a professional.

The boiler is now finally fixed, needed a new expansion vessel.

Not without them leaving a gas leak when they changed a water pipe a few days earlier. They took the gas pipe off and left a leak, had SGN out and they said it was due to this leaking pipe inside the boiler. I then proceeded to complain to the company that provides my cover about this, and the manager of the company, didn't take kindly to this and started to moan about how much the repairs had cost him thus far and that I only pay 'X' a year....

Great company... I pointed out that if they had done their job correctly in the first place it wouldn't have cost his company so much money in labour etc.

So my next question is, can this company be reported about the gas leak to a relevant authority? I'm in Scotland btw.
 
I would think so as they should have tested for gas security during the commissioning stage. if it was the expansion vessel at fault, you should have seen water being discharged from the vent pipe, you did test for this. For when they return, get a hitching rail outside for them to tie up their horses.
 
I'm glad it's all sorted, but it's still a mystery to me how those symptoms were caused by a faulty expansion vessel. I'm guessing it's an internal EV (as in built in to the boiler), so probably around 8 litres. In a correctly balanced system, that's 4 litres of air and 4 litres of water each at somewhere around 1 bar. If the EV was faulty, the diaphragm was pierced and the water ended up flooding the entire EV, so 4 litres of water from the CH system displacing 4 litres of air. This seems reasonable when the CH system was still connected, but it doesn't seem reasonable when it was isolated, but not when it was just the water in the boiler. Where was all this water going on each subsequent repressurising every morning? I guess we'll all remain in the dark on this one, unless someone can provide an explanation that puts us out of our misery.

Did they also happen to replace the filling loop with its double check valve? I've had both ends of a filling loop fail before, which contaminated my drinking water with CH water when the pressure in the CH system rose to be higher than my mains (which are regulated to 3 bars).
 
Mike83 said:
If you have Allen keys try. I'm sure they do fit inside.
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I'm not sure what these people are talking about but if you have a 24 hr leak you will see the water on the ceiling or get a plumber to check under your floor. Usually it is in a cemented floor and a big job I have just had the same on a gas pipe in a council house kitchen but both the gas and hot water had decayed causing water to go in the gas pipe . I was able to save the boiler but the fire and cooker had water in them . It's the expansion of hot water not lined pipework check for leaks or water marks on solid floors check all heating pipework you can see ceilings rad valves . It's a hard 1 to fing if your lucky you can buy leak sealer put in when boiler is off then fire up heating
There is no leaks on the boiler you would see water and on valves you would see water . As I said going through a brick wall without a linner is the most common problem thankssh
 
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