Flue Exit - Height From Ground

[MrFrisbee]

If I were installing this boiler we would look at a brick enclosure outside to allow the internal flue to run outside, but inside, as suggested.

The alternative is a Keston, but they are pony and trap.

The PRV will need to discharge into a steel tank below ground.

If you dig a well there is still a danger of leaves or snow compromising the boiler inlet, which will be difficult to justify to a Gas Safe inspector.

The plan is to let the PRV outlet into an existing sump (plastic) that has a pump in it which pumps out when levels are high. It is mainly there for flood protection.

There is no plan to dig a well, just a small trough below the air intake of 10cm to give it clearance of 30 cm in total.

Charles.

 

[simond]

If the trough was small enough to block with leaves or snow, then I don't think it would suffice. It will work for sure, but there may be an issue when you sell the property and if I were the installer, I would not be happy self-certifying it.

The blow off arrangements into a plastic sump do not pass muster either; you could be talking about temps up to 100C and your pump is not going to be rated at anywhere near this.

Some sealed boiler manufacturers allow you to plumb the internal PRV into the boiler return and then site another PRV above ground. Others expressly forbid this, Worcester and Vaillant for instance. I don't know what Alpha stipulate because we don't specify their gear.

In which case it has to be a steel tank capable of carrying all the water in the rad circuit. Whether you add a pump (or a drain off) is purely a matter of convenience.

 

[sooey]

In which case it has to be a steel tank capable of carrying all the water in the rad circuit.

Simon, why is? Surely the pressure will have dropped enough to close the prv long before the system is empty.

 

[MrFrisbee]

In which case it has to be a steel tank capable of carrying all the water in the rad circuit.

Simon, why is? Surely the pressure will have dropped enough to close the prv long before the system is empty.

This was my thoughts when I was told I may need a large (10 gallon) tank below the boiler.

The tank that is there now is about 20 gallons and has a cast iron pump in it. The PRV will surely only blow off a minimal amount of water and there is always about 10 litres in the sump anyway that never gets pumped out.

Charles.

 

[simond]

I agree it is crazy. But so many things are in our business. We've been told it has got to be a steel (or otherwise heat proof) tank capable of taking whole system volume.

I don't see why Bosch and Vaillant won't let an installer relocate the PRV one floor up....but apparently Poxi Batterton will.

If it's an unvented blow off then we are looking at a steel tank and a high temp pump. Try buying a pump that is rated at near the possible blow off temperature.