Central Heating Question

Should central heating and hot water work independently?

I have just purchased a new home, and have a question relating to how the Central Heating and Hot Water systems should work.

The boiler is a Baxi HE 24 Solo. The programmer is a Honeywell ST6400C. There is a hot water storage tank in the airing cupboard, which I presume is gravity fed from the loft.

The issue is that, in order to get central heating, I seem to be required to have the hot water on at the same time. That is, if I turn the heating on using the programmer, it won't deliver heat through the radiators unless the hot water is also on, as controlled by the programmer.

In theory, I only need hot water in the morning, so would like to have the hot water only active at that time. In conjunction, I would like to have the heating come on as dictated throughout the day by the programmer and thermostat. Ideally I would like to move to a Nest thermostat for the heating, so would require the heating and hot water to work independently.

It seems very energy inefficient to have to heat the hot water tank every time I want to use the central heating. Especially given I only need hot water in the morning for showers.

Is this simply a mis-understanding with how this particular type of system has to work in order to deliver heating, or is there an issue with the wiring between the programmer and the boiler? I have tested the thermostat and that is fine.

edit: as per the below answers, it seems the first step is to determine if it's a semi or fully pumped system. Is there an easy way to do this? I've noticed a two way motorised valve next to the hot water cylinder. At a guess, this would only be there if it's a fully pumped system (hence likely a problem with that valve)?

edit2: The valve is inline, i.e. one pipe going in and one pipe going out. It is connected to the pipe which comes out 2/3 of the way up the cylinder.

edit3: The pump is situated directly above the boiler. There doesn't appear to be any more valves, either by the boiler, or by the cylinder.

finaledit: A heating engineer came round this morning. Informed me it was currently a semi-pumped system and the valve next to cylinder was running direct to the room thermostat i.e. it would close the valve when the rooms were at temperature. He recommended upgrading to a Y-plan fully pumped system, which requires him to move the pump from its current location and do some pipe work by the cylinder. thanks to all who advised.

4 Answers

Best Answer

It sound as though its a motorised zone valve problem. Call a Heating engineer out. Ok. So you have found a motorised valve. Is it in line ie one pipe in one pipe out or has it got one pipe going in at bottom and two pipes coming out of the side.presuming its installed the right way up. If that valve only goes to cylinder then its not the one at fault. There will be an other.

Answered 11th Nov 2014

MCD Installations

Member since 3 Nov 2014

It seems as though your programmer may either be faulty or set to gravity only. Also a chance like the previous that you may have a faulty motorised valve. They only way to be sure is yo check the movement of the valve(s) when turning heating and hot water on/off or remove programmer (making sure electrics switched off first) to see if the programmer in question has been set to fully pumped. If you have a motorised valve then yes it would be a fully pumped. (Unless someone has really messed). Yes that seems to be fully pumped! Where is the pump situated? Yes it seems as though it is fully pumped. So need to look into weather the motorised valve is faulty, if the programmer is set to work as fully pumped.

Answered 11th Nov 2014


Member since 11 Nov 2014

You may have gravity hot water and pumped heating, an older design but many still about.

Answered 11th Nov 2014

Heat Central

Member since 20 Oct 2014

i agree with all of the above the programmer is designed to heat hotwater and heating independently or together so its pointing to the valve but you will require a vist to determine this

Answered 26th Jan 2017

All Heating Solutions

Member since 14 Mar 2016

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