Central Heating pressure

[Houseman]

Hi
Worcester Bosch Greenstar Ri (Condensing boiler)

Just had a pressurised system fitted and occasionally the boiler won't fire from cold.

What is the minimum pressure to fire it up?

Is the pressure in a vented system the same when cold?

Thanks

 

[KenGMac]

Houseman, good evening.

Suggest you have a look at the operating manual for the minimum pressure needed for a fire up.

OK I am not a heating engineer, I will probably get SHOUTED at by more qualified on this board???

I have generally been told that a cold pressure of 1 Bar is where the pressure should be.

BUT? why is the system loosing pressure?? If this is a "new installation" then there looks as if there is a system leak somewhere.

How often are you having to re-pressurise?

Ken.

 

[MeldrewsMate]

Houseman, good evening.

Suggest you have a look at the operating manual for the minimum pressure needed for a fire up.

OK I am not a heating engineer, I will probably get SHOUTED at by more qualified on this board???

I have generally been told that a cold pressure of 1 Bar is where the pressure should be.

BUT? why is the system loosing pressure?? If this is a "new installation" then there looks as if there is a system leak somewhere.

How often are you having to re-pressurise?

Ken.

I'm not shouting Ken, thanks for trying to help the OP, and also for knowing your limits.

OP, the system pressure will rise as the system water gets hot, but the range between cold and hot should generally not exceed 1 bar (so 1 bar cold, 2 bar hot). If it exceeds this then either there is not enough expansion capacity on the system, or there is a problem with the existing expansion vessel.

 

[Madrab]

Always best to have it at least 1 bar @ cold.

That being said, I'd be getting the installer back in, they should have explained the system and it's requirements. If it's a very recent install then it could be the system settling out but again that should have been explained to you.

 

[dilalio]

Maybe the installer had concerns regarding springing a leak on old pipework that was previously gravity fed!
That's always an inherent risk and should have been explained to you.
Still, a minimum pressure is required for boiler to fire.
Maybe it was set to 1.x bar and has dropped due to settling or there is a leak.
I would suggest getting them back, so that you can't be accused of tampering.

 

[Elkato531]

The greenstar Ri does not contain a pressure switch. It is designed as a heat only boiler for a vented system which can be pressurised, if required, by adding external components. It should fire regardless.

 

[dilalio]

The greenstar Ri does not contain a pressure switch. It is designed as a heat only boiler for a vented system which can be pressurised, if required, by adding external components. It should fire regardless.

Thanks. Not familiar with the boiler and didn't look it up. So, apologies to the OP if this misled.
Even more reason to get the installer back then.

 

[Madrab]

I think it was the pressurised system comment that threw me too - didn't even think about it either TBH -DOH!!