Safety converting from open vent to sealed

[tobybuk]

Hi

I'm in the early stages of planning a major extension/rebuild of our house. We have an Oil boiler house boiler (Grant 70/90) open vent system and I'm thinking of reusing this boiler with a closed setup.

My question concerns safety. In my current setup loss of water from the heating side would get topped up from the header tank. However on a sealed system this isn't the case and as I understand its up to the householder to periodically check the pressure and top up via the filling loop if required. But if I'm reusing my current boiler it has no flow or pressure safety cut-off to stop the boiler firing if its dry - which I think most sealed boilers do.

So my question: What do people normally do when considering such an install. In my simple mind I assumed you'd be able to buy a pressure or flow sensor and wire that in to the boiler call circuit - but since I cannot find any of these online I guess it either not the done thing or not common.

Any thoughts?

Thanks

 

[jeff the gasman]

Check the boiler installation manual to see if the boiler is suitable for sealed system, if it is, crack on.
Low pressure is not an issue and the system will make you aware if it gets too low. The boiler limit stat will operate if there is a problem. You need an expansion vessel and PRV.

 

[simond]

With an oil boiler it is not considered such an issue on small domestic, for starters the oil boiler has a high water content.

Grant do make an optional pressure monitoring kit, we've just fitted one to a new external Vortex we've just installed. If the boiler is the lowest point in the system, it is unlikely to run dry. And you don't find many oilers in the roof space.

Cost for the kit is around £40 and it is a bit of a pain to install, although everything is easier with an uncased boiler house model. This is the internal version;

http://www.grantuk.com/wp-content/u...w-pressure-switch-DOC70-Rev03-August-2010.pdf