GCH room thermostat

[Tommo]

I've just had a combi boiler installed (Baxi 105e) and the installer never installed a room thermostat. He just said to use the controls on the boiler to control the time etc and to adjust the TRV's in each room for the temperature. However when we got gas central heating in a previous house, we had a separate control box that the temperature etc could be set on and it was ideal.

I've been looking at the Honeywell CM927 wireless thermostat

to its instructions, there are only 4 wires to connect. Is it really as easy as this? Are the T1 & T2 connections easily found on the boiler?

Many thanks.

Tom

[John Stumbles]

Looks as if that's an OK configuration for this boiler: it has a built-in bypass valve which should tell the boiler that all the TRVs have turned off and stop the boiler firing until there's a demand again. (Presumably it keeps the pump running either continuously or intermittently to detect this.)

Personally I think it's a lousy way to run a system because the only control you have is ON or OFF whereas a programmable thermostat gives you more flexible control of time/temperature, but IMHO it's probably a lousy boiler too (it seems to be a missing-link design between the sort of truly-appalling condensing boilers with bolted-on secondary heat exchangers and current-technology with compact HXes with blown gas/air mixtures).

the best choice: I've not fitted that model but have done several of the wireless versions of the earlier model (CM67rf) and have fitted some of the CM907 wired versions.

Yes: see p22 of the manual which your installer must by law have left with you when he installed the boiler. You should be able to connect all 4 terminals of the CM927 relay unit to the terminal block in the boiler. Multi-core heat-resistant cable is the thing to use though you probably won't find that at B&Q!

[Lurch]

On Sun, 4 Mar 2007 17:22:06 -0000, "Tommo" mused:

Easier still would be a Baxi wireless programmable stat. Plug the one bit into the front of the bolier, screw the other bit to a wall somewhere.

[Hugo Nebula]

On Sun, 4 Mar 2007 17:22:06 -0000, a particular chimpanzee, "Tommo" randomly hit the keyboard and produced:

Can I ask the Central Heating installers in this group why this kind of thinking persists?

Since 2002 this kind of set-up with no interlock has not been permitted in installations to which the Building Regulations applied, and was good practice befor this date. Yet it is allowed to persist in installations which are not inspected by Building Control, as witnessed by the above, and a similar replacement boiler in my mother's house a couple of years ago. I have also picked up installations like this in properties I've inspected.

Is there no requirement for CORGI-registered installers to regularly update themselves on changes to regulations and good practice? Or does CORGI only concern itself with gas safety, and let other issues go hang? It seems to me to be driving a coach & horses through the Government's carbon reduction policies to require all new boilers to have minimum efficiency ratings, then allow the installers to set them up in the most inefficient manner possible.

[Ed Sirett]

In theory all CH installers should have training and assessment in "Energy Efficiency" (C&G 6093?) I think. I certainly have done so, I pretty sure Mr. Stumbles has. This is on the 'guild' membership card (CORGI, OFTEC or whatever).

It's hard enough to get the message over "If they don't have a card don't let them in", let alone the message "If they don't have the right qualifications don't let them in." In practice any old CORGI might have installed the OP's system possibly before the requirements filtered down to the fitter-in-his-van.

Last year I had a part time job trying to get a firm of builders up to the mark on CH installs. Time and time again when I find a system which has been installed by 'a builder' there are these faults and they are always the same:

No TRVs fitted. No wall thermostat fitted. Electric cable or flex less than 25mm from gas pipe. Inadequate sized gas pipes (especially for combis). Liberties with the blow off pipe.

[Tommo]

> Probably the best choice: I've not fitted that model but have done

Thanks for the info John. I found the details in the manual you were referring to. It looks simple enough with just the 4 wires needing connected. I had the choice of any boiler from the installer or buying the materials and the installer fitting them for me but he recommended the 105e as he hasn't had a minutes bother from the countless ones he has already fitted.

Hopefully it will be better than the Vokera I had installed in my last house. The gas board were out at it, at least once a month.

Tom

[Tommo]

I hadn't come across the Baxi one until I saw your posting. Looks extremely dear for what you get.

T.

[Tommo]

It was a few folk from Scottish Gas doing it in their own time so I would have imagined they would be well versed in the requirements. They were probably trying to keep the costs down to a bare minimum.

T.

[John Stumbles]

6084. Not rocket science but a step in the right direction.

Looks like Poxi-Batterton are trying to alleviate that one by making it unnecessary (and of course the controls wiring then becomes not notifiable under Part P because there isn't any).

In an ideal world Worcester and Vaillant would build-in decent wireless progstats (Honeywell by preference for me) at street price and then we'd all be happy!

[Lurch]

On Mon, 5 Mar 2007 22:19:41 -0000, "Tommo" mused:

Not sure on prices between the 2, just that on all the Baxi's I've wired I've been supplied wth one of the Baxi wireless kits. Obviously both will work, pick whichever suits your circumstances. ;)

[John Stumbles]

It'd be interesting to check out the CORGI registration number they put on the paperwork and on the certificate you got from CORGI to confirm that the installation has been notified under building regs. If they're SG employees their registration is for working as such: if they don't have their own registrations (at least one between them) for doing work privately they're legally unregistered.

[John Stumbles]

Which he's been fitting for, what, coming up to 2 years now? :-)