Pressure gauge central heating problem

awishawash

Hey everyone I am having a problem with the pressure gauge above my boiler, beside the pump. Its the yokey you top up with water to increase pressure in the system. The central heating is working fine. However, the gauge seems to increase slowly when the heating is turned on. I then have to let water out to bring it back down to the correct bar.
I thought that there may have been water leaking in to the system but as it only happens when the heating is turned on, I can discount that.
Any ideas?

rooferPete

Hi,

As water heats it expands and as your system is sealed it has to increase the pressure.

Have you let the heating run without letting out any water ? the worst that should happen if your system is too full is the pressure will release at the pressure release valve (with the black plastic cap).

If it does let the water out (Carefull it's boiling hot) that would suggest to me your system is letting water or air in some where, unlikely though the problem is usually too little pressure.

Maybe Jim or Pipers can correct me.

.

JamesM

rooferPete wrote:

Hi,

As water heats it expands and as your system is sealed it has to increase the pressure.

Have you let the heating run without letting out any water ? the worst that should happen if your system is too full is the pressure will release at the pressure release valve (with the black plastic cap).

If it does let the water out (Carefull it's boiling hot) that would suggest to me your system is letting water or air in some where, unlikely though the problem is usually too little pressure.

Maybe Jim or Pipers can correct me.

.

Pete is correct above.
There is no harm in the gauge going from just below 1 most of the way up to 2. Although just on 1 is ideal. If you let out water, to bring it back to 1, does it go below 1 when it cools down ?
It could be that, if the fresh water comes from the mains, you are not turning off the valve when the system fills up, or that the valve is not closing fully and the mains pressure is forcing more water into the system. What often happens is: The system is hot and the pressure is fine. The system cools down, the water contracts, and the mains pressure forces more water into the system. There is a non return valve fitted, so when the water heats up the next time the heat is turned on, it expands, sometimes so much that the pressure release valve blows. This can be messy and sometimes the valve does not sit back down and continues to leak.
Jim

awishawash

Thanks for the response lads I havent had time to troubleshoot the problem but will keep you updated..

awishawash

Hey lads the boiler is indeed just increasing pressure as the water heats. And it drips from the overflow because of this.
The boiler shuts off every 10 mins or so and then back on again, as if theres a drop in gas flow or something, but I vaguely remember reading sumthing about the boiler establishing a temperature then knocking the gas off until it needs to reach that temp again. Sound right?

jd

awishawash wrote:

Hey lads the boiler is indeed just increasing pressure as the water heats. And it drips from the overflow because of this.
The boiler shuts off every 10 mins or so and then back on again, as if theres a drop in gas flow or something, but I vaguely remember reading sumthing about the boiler establishing a temperature then knocking the gas off until it needs to reach that temp again. Sound right?

What pressure is it at when it is cokd? Once the water reaches the reqd temp it shuts off..

JamesM

awishawash wrote:

Hey lads the boiler is indeed just increasing pressure as the water heats. And it drips from the overflow because of this.
The boiler shuts off every 10 mins or so and then back on again, as if theres a drop in gas flow or something, but I vaguely remember reading sumthing about the boiler establishing a temperature then knocking the gas off until it needs to reach that temp again. Sound right?

The thermostat switches on and off to keep the boiler at the required temperature - that is normal.
As jd asks, what pressure is the gauge showing when the system has fully heated. It should go above 3 before it blows. If it is leaking at 2 or less, the safety valve is faulty. The seal may be worn. Sometimes you can screw another valve into the first one. this stops the leak and the new valve controls the pressure. If this cannot be done, then the whole system may have to be drained to change the valve. If the pressure in the system is going above 3, then too much water is getting in. See what I said before about the mains etc.
Jim.