CH system - do I have a bypass already?

[garmcqui]

Hi all,

This weekend I'm swapping our heating controls over to the Honeywell Evohome system, so I'll end up with about 8 zones which can be individually controlled.

Problem is, we currently have two radiators (upstairs and downstairs in the hall) that have no TRV's fitted.

When I spoke to a couple of Honeywell installers, they both recommended having an Evohome TRV on ALL radiators, but only if you have a pump bypass fitted (so when the pump overrun is active, the water has somewhere to go).

Being a new build house (built April 2014) they both thought it likely that the bypass was already there, but obviously couldn't say without checking first.

So I'm just wondering, can anyone tell by looking at the plumbing around the unvented cylinder below:

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(I've tried to add some annotations to show what I think is the correct water flow direction etc, based on the cylinder manufacturer's manual).

I think there is a bypass already there, but if so why were the hall radiators left TRV-less?

Thanks!

Gareth

 

[stardanny]

There is a bypass valve behind CH to Zone 2 pipe.

Do you have a room stat in hall? If yes, that is the reason why it got to be manual radiator valve so only the room stat can control temperature of heating.

If you fit TRV in hall, TRV will shut heat to hall radiator if the hall is warm enough but not enough for room stat to shut off boiler. This is the same for upstair landing if there is a room stat as well.

Daniel.

 

[garmcqui]

ah, you mean this little fella?

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[Dan Robinson]

Yep.

 

[stardanny]

Yes.

Daniel

 

[garmcqui]

Cheers lads

Just realised it was listed as being item 7 on the diagram I was looking at anyway. Jesus I can be blind sometimes.

So... my next question...

There are two thermostats attached to the cylinder, one halfway down which controls the hot water temperature (currently set at about 60C) but there is another at the top left of the photo, near the top of the tank. I've identified it as a safety cut out thermostat, but tracing the cable back it seems it has nothing to do with the central heating system, it goes to the solar heating controller?

Does this mean this safety thermostat is only there in case the solar system heats the tank too much (not bloody likely in Newcastle!)?

Ta