Unable to have hot water without heating - I'm melting!

[WhenIGrowUpIWantToBeAPenguin]

I live in a house owned by my DDad, whilst he lives elsewhere. The house has a very old (but functioning and reliable) hot water/heating system (boiler, hot water tank and loft water tank). My main issue is that the system control only allows both heating and hot water at the same time, so in this hot weather to have hot water I also have to have the central heating on! There is no thermostat, the radiators are controlled individually with knobs on each one - but most of these don't seem to switch totally off so the radiators are warm (and some hot).

I know there's no quick fix, and in other weather it's bearable but what is my best option long-term? Is it possible to replace control system only, and would a new control be compatible with the remaining old parts?
Also - what ballpark costs should I expect? I'm not paying rent so my feeling is that it's only fair that I pay not my dad.

If I go ahead, I'm conscious of how little I know about this sort of thing and want to sound at least a little prepared if/when I meet tradesmen.

We had this too! It turned out to be a value (or something like that!) that was on the pipes by the boiler. A new one cost us £60

Wasn't the big expensive job I was expecting!

quite a lot of knackered stuff in that house.

if you turn the radiator valves to 0 are the radiators still warm? If so the valves (thermostatic radiator valves or TRVs) have failed, which they do after about 10 years. They will all need replacing, about a tenner each for the part.

if the system controls really only allow HW with CH on as well, then that is all you can do. If the controls should allow them separately but don't, then guessing your diverter valve has failed. About £100 to have replaced.

if there is no room stat, then you need one.

Ask around for a recommended local heating engineer (or an experienced plumber, as this does not involve gas work).

You probably need a 3-port or 2-port valve. Maybe there is one and it is faulty.

It is probably possible to fit a new timer/programmer, but if you are getting a room stat (which will save money and improve comfort) go for a programmable one which incorporates its own CH timer. It will turn the CH pump on and off when required, via the motorised valve, if there is one (some old systems do not, which is less efficient).

The Honeywell CXM907 is exceptionally good.

Some people like wireless stats, but they go wrong more often.

CM907

Not "x"

Is your shower electric or run off central heating?

Boil kettle if you need hot water for washing up etc.

Yes radiator valves should be fixable quite easily. DH has replaced several of ours that stick.

If you have old eccentric heating it may not be possible to remove the problem completely. Our system requires one non thermostated radiator.

We use the bathroom one, and dry towels over it. Annoying when it's this hot be fine normally.

Hi all, massive thanks for all your advice. Just as an update, having reviewed my options and looked at all the current problems, I've decided to overhaul the entire system, including:
New combi boiler (old one is a back boiler behind a gas fire, which I'm also going to remove) - I'm looking at Ideal logic HE24 kw - any opinions on this?
New radiators in all rooms - I have a massive radiator in a small bedroom, and one small radiator covering the entire downstairs, stairs and landing so will get better-sized new ones and install an extra one downstairs.
New control panel/timer with room thermostat - thank you PigletJohn, I will definitely bear your recommendation in mind.

So, hopefully, the new system will be more economical as well as working properly! Again - thanks for all your advice - it gave me much more confidence when it came to working out what I wanted to do and speaking to tradesmen

If I were you I would reconsider your boiler choice - although they are relatively cheap to buy. The Ideal boiler in our old house, which we still own and rent out, needed a new circuit board after 5 years. The circuit board is an expensive piece of kit, costing 250. If you google reviews you will see that a lot of people think they are rubbish!

In contrast the Worcester Bosch boiler in our current house has fared much better over a much longer period of time.