Following on from an earlier discussion about combi boilers having modulating pumps which sensed back pressure as TRVs closed: Is it still necessary to have a heat dump, traditionally a towel rail. with these combis? Or can all the rads be closed when the system is satisfied?
AJH
It will vary with boiler. Some have an internal bypass to facilitate operation into a completely obscured primary circuit.
However remember the need to provide a boiler interlock... since this normally a room stat, it would be normal to have no TRV on the rad that shares a room with the stat anyway.
Some boilers - including some Poxi-Batterton models - can be used on all- TRV systems without a roomstat, for cheap'n'nasty penny-pinching installs.
I thought Part L or whatever specified at least one room-stat?
It requires a boiler interlock - that is usually done with a room stat, but can be done by other methods.
Yes but the Poxis are designed specifically to get round that.
Despite being crap boilers that is good design.
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