Combi boiler loosing pressure fast

[Nathzy01]

Hi all, back again with yet another question about my grant vortex combi boiler

Sorted all previous problems and was running sweet until recently… now it’s loosing pressure really quick, from 1.5 bar down to 0 in a couple of hours (even when on standby neither hot water or central heating selected).

There are no leaks internally in the house as would be flooded by now with the amount I’ve repressurised and haven’t used CH in a few weeks. Definitely no leaks inside the boiler on joints, valves, prv etc… also no excess leaking from the condensation pipe.

There is a damp patch surrounding boiler on the concrete base it’s sat on, could it be a possible split/corroded water tank? Though there does seem to be droplets on the boiler lid, suggesting maybe condensation from inside?

The only other thing I can think of is the expansion vessel, but wouldn’t this cause pressure to increase when heating up? It’s not leaking water through the valve… the pressure loss is within 2 hours from 1.5 bar to 0.

Any pointers would be greatly appreciated!

 

[exedon2]

Which model grant? and age?
Have you isolated heating from boiler? If you have a vortex pro you can turn of heating return on boiler (blue handle on valve) and isolate flow by turning of pump valves on heating pump.
Tho in truth the damp patch under boiler probably indicates a leak on hex or more probably heat store tank.
Worthwhile checking expansion vessel pressure and be absolutely certain prv is not passing.

 

[Nathzy01]

thanks for the reply. It’s a grant vortex 26. It’s about 12 years old, so getting on now it was in the house when I bought it. But has been maintained and also pretty much every part changed on it recently by myself.

The CH has been isolated and still dropping pressure. But doesn’t look like a huge amount of water underneath just a damp patch, also some droplets on the lid and insulation so have removed and left open today to see if it dries up and rule out condensation. As I remember last summer was a damp patch but never lost pressure.

I assume store tank would be new boiler time?

Would expansion vessel cause such a fast drop in pressure?

Thanks again

 

[exedon2]

If expansion vessel needs to be re pressurized /replaced yes it can dump pressure very quickly through prv.
If heat store / boiler is leaking yes new boiler time as I know Grant consider it not viable to change.

 

[Nathzy01]

If expansion vessel needs to be re pressurized /replaced yes it can dump pressure very quickly through prv.
If heat store / boiler is leaking yes new boiler time as I know Grant consider it not viable to change.

It’s definitely not dumping through the prv or condensator pipe, though the expansion vessel is loosing pressure also but not passing water. Just trying to rule one out.

Are the heat stores known to leak? It doesn’t look like a huge amount of water coming out what I would expect from the tank. I have attached a pic.

 

[exedon2]

I would bet that's a leaker
Bottom of heat store
Don't see that many on Grant's but not unknown.
When you replace make sure system is properly flushed and a decent system filter fitted (easily fitted in space next to condensate trap)