Grant Vortex Combi boiler problems

[ijb2302]

Hi
I have a Grant vortex 26 combi oil boiler. It is about 5 yrs old and has a couple of issues.

1. It doesn't seem to hold its pressure. I pressurise the system to 1bar but in a couple of days it reduces to almost zero but not low enough to trip the LP switch. There is a discharge from the PRV that must happen during normal operation. I have bled the system at the boiler and radiators and I have checked for leaks but can find none

2. The domestic hot water occasionally runs cold even when demand is low e.g. washing up.

I would appreciaye any help

Ivan

 

[Terrywookfit]

Check the charge on the exp vessell

 

[ijb2302]

Thanks I will try that.
I actually fitted anew one a year ago. The other was filled with water.

 

[ijb2302]

I checked the exp vessel pressure and it was 0.95bar.

The system pressure was low again. I filled it to a preesure of 1 bar and fired the boiler. The pressure went up to 2bar+ and the PRV vented.
It seems that there is not enough capacity to cope with the expansion of the fluid.

Should I pressurise the system to to a lower pressure say 0.5bar

 

[Terrywookfit]

Did you completely de pressurise the system before checking the vessell ?

How many rads are on the system.

An additional 18 litre vessell would help, as the one fitted as standard is only big enough on a small system.

 

[ijb2302]

Thanks for this

Yes I de-pressurised the system.

There are 11 radiators. I have calculated the volume when I installed the boiler as around 80 litres which should be within the Grant stated maximum of 128 litres.

I notice that this is at expansion vessel charge of 1 bar and system pressure of 0.5 bar.

I have just checked after about 4 hours of operation.

After starting with the exp vessel pressure of 1 bar and system pressure of 1 bar when cold about 1 litre of water has discharged via the PRV and the system pressure (hot) is now 0.5 bar.

 

[dcawkwell]

Thanks for this

Yes I de-pressurised the system.

There are 11 radiators. I have calculated the volume when I installed the boiler as around 80 litres which should be within the Grant stated maximum of 128 litres.

I notice that this is at expansion vessel charge of 1 bar and system pressure of 0.5 bar.

I have just checked after about 4 hours of operation.

After starting with the exp vessel pressure of 1 bar and system pressure of 1 bar when cold about 1 litre of water has discharged via the PRV and the system pressure (hot) is now 0.5 bar.

What pressure have you got in the expansion vessel now?
If it has dropped the expansion vessel is at fault.
Faulty tyre valve on the expansion vessel possible.

 

[ijb2302]

The exp vessel pressure is still 1 bar so I think it is OK. It was new a year ago.

 

[slapper]

Thanks for this

Yes I de-pressurised the system.

There are 11 radiators. I have calculated the volume when I installed the boiler as around 80 litres which should be within the Grant stated maximum of 128 litres.

I notice that this is at expansion vessel charge of 1 bar and system pressure of 0.5 bar.

I have just checked after about 4 hours of operation.

After starting with the exp vessel pressure of 1 bar and system pressure of 1 bar when cold about 1 litre of water has discharged via the PRV and the system pressure (hot) is now 0.5 bar.

Why dont you fit a new PRV,it shouldnt discharge at less than 3bar and or 90degrees centigrade

 

[Tibbot]

There are 11 radiators. I have calculated the volume when I installed the boiler as around 80 litres which should be within the Grant stated maximum of 128 litres.

Did you remember to allow for the 50 or so litres contained in the boiler in your calculation? That leaves only 78 to fill 11 rads and pipework. Extra vessel is probably required.

 

[dcawkwell]

Faulty pressure relief valve if it discharged at low pressure.

 

[ijb2302]

There are 11 radiators. I have calculated the volume when I installed the boiler as around 80 litres which should be within the Grant stated maximum of 128 litres.

Did you remember to allow for the 50 or so litres contained in the boiler in your calculation? That leaves only 78 to fill 11 rads and pipework. Extra vessel is probably required.

Thanks that is a good point. I had not allowed for the boiler capacity so I am right on the limit. So it looks like another exp vessel.

Where be th best place to put it? The boiler is in a boiler room.

 

[ijb2302]

Faulty pressure relief valve if it discharged at low pressure.

Thanks. I have checked the PRV and it is OK

 

[Terrywookfit]

Tee into the return pipework in the boiler room.

I would use an 18 ltr.

 

[orinvolucri]

We had a Grant combi boiler which 'blew up' in 2008 ruining much of the contents of our garage with dirty water leakage. It was replaced with a Grant vortex combi 26 by our plumber and has been trouble ever since. We've had a PCB replaced and the pressure always drops after a week or so well below 1 bar meaning the heating and hot water do not come on. It requires resetting every time which the subcontracted Grant engineer showed me how to do.

However, in using the one years extended warranty through Grant, the engineer found no fault indicating that we had to pay £235 to Grant. Their engineer only charges £57 call out fee! So, we are left with court case to fight (which we are presently doing) and a boiler that clearly has something wrong such as a faulty pressure vessel, pressure switch or similar. Moral of the story from our experience - avoid Grant boilers.

Any advice on how to proceed (legally and plumbing wise) would be greatly appreciated.