Dripping tap and pressure loss

[pinheadplanet]

Hi

Is it possible that a dripping hot water tap can cause a loss of pressure in the boiler central heating system?

Ta

K

 

[twgas]

very unlikely

 

[MANDATE]

As your 'hot water' is really 'mains cold water' heated up by boiler, it is at mains pressure which is higher than the system pressure.
A pinhole in heat exchanger could make pressure rise, but loss of pressure No!
If you're losing pressure, the question is how much over what period and is this with heating on or off.
The problem is most likely a problem with the expansion vessel, it may have lost its charge.
The pressure will probably have risen to 3bar and opened the PRV.
Even if action has been taken to rectify the above problem, it is likely the PRV has not closed properly due to sediment and is still allowing a drop in pressure but at a slower rate.
If the expansion vessel and PRV are in good working order then there is a leak elsewhere. (radiator valves maybe)

 

[pinheadplanet]

I've been keeping a bottle at the end of the PRV outlet to monitor any release and there's not really been any now. However I haven't seen the pressure go upto 3bar, when I started to lose pressure it was at about 2.5bar maximum so I don't think the prv should have been activated.

I'll check the valves.

Can I check the expansion vessel pressure with a tyre gauge for a car?

I haven't seen any evidence of water loss anywhere.

If I fill the system upto 1.2bar I will lose it down to about 0.6bar in a few days with the heating on.

 

[big-all]

any bleeding off radiators will reduce the pressure and need recharging
have you been bleeding any radiators or noticed any leaks??

 

[twgas]

I've been keeping a bottle at the end of the PRV outlet to monitor any release and there's not really been any now.

does this mean there has been a little leakage from the pipe or none at all?

 

[pinheadplanet]

There's been a tiny amount of water (2mm) in the bottle but this could just be from rain water running down the outside of the pipe rather than from the prv having been activated.

Previously when the prv has opened there's been a considerable amount of water in the bottle.

I've not been bleeding the rads.