Heating controls - is my electricial having a laugh at me?

[Tommy Gilchrist]

Folks

Summary - Switching on central heating doesn't start gas boiler, hot water needs to be switched on as well - electrician claims this is the normal way these things are configured. Is he talking through his..?

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I'm just getting to the end of a bit of a renovation and while I was doing it I had my hot water system replaced with a pressurised system.

The existing natural gas boiler was retained and the central heating hasn't been pressurised.

The electrician onsite fitted a new control system but when I went to test the system (he'd already left) I discovered that putting the central heating on switched on the central heating pump but didn't fire up the boiler. Switching on the hot water fires up both the boiler and the hot water pump.

I called the electrician and explained the situation and he tells me that this is the way it's supposed to be, if you want the central heating on you have to set the hot water to come on at the same time.

This certainly wasn't the case with the old system and I think he's having me on but he's so adamant about it that he's got me doubting myself. He says he can set it up the way I want i.e. either can be on independently but it will be really complex and require a relay, etc and then started to try to baffle me with electrical terms (I hadn't the heart to tell him I have a degree in Electrical and Electronic Engineering - I wouldn't make any claims to be an electrician but I know enough to know it sounded like crap)

Could anyone offer an unbiased opinion? I don't want to start a fight with what have otherwise been a great team of builders.

thanks

tommy

[Dave Plowman (News)]

He's talking bollox. ;-)

Do you know what wiring plan has been used? Have you a three port valve, or motorised valves, or none at all?

However, on the most basic system which relies on gravity circulation for hot water heating the hot water will work on its own while the central heating only comes on when the pump runs. If a fully pumped system - which it sounds like you have you if the pump runs for the hot water - it's a wiring etc fault if you can't have heating without hot water. You can have either or both with this system.

I'd guess there is a link missing in the programmer, if it's Y plan (three port valve which is perhaps the most common)

Have a look at this site which shows that link or do a Google for lots of others.

newsgroup's FAQ gives the common wiring diagrams too.

[David Hansen]

On Sun, 09 Jul 2006 11:29:05 +0100 someone who may be Tommy Gilchrist wrote this:-

No quite.

In Ye Olden Days heating systems were wired up so that the "hot water" control activated the boiler. Water would circulate to the cylinder by gravity. The "central heating" control activated the pump for the heating, via a thermostat. Simple, but not ideal.

When you "had my hot water system replaced with a pressurised system" what work did they do? I assume that they fitted a thermal store in place of the cylinder, or did they fit a multipoint heater?

[Tommy Gilchrist]

There is a single pump and a single motorised valve. The pump sends the output of the boiler to both the unvented cylinder and the radiators but the motorised valve sits between the output and the radiators.

(Kitchen fitting for the next day or so)

[Christian McArdle]

It is now a legal requirement that the heating and hot water controls are independent. The system as installed does not comply with Part L of the building regulations.

Christian.