If I switch the heating on but turn the stat on the hot water tank down so it doesnt heat the water will I break the central heating?

[Fluffycloudland77]

I just thought I'd check before I do it.

no

why?

Are you giving it a chemical clean?

No, but we dont need loads of hot water and I want to keep the bills down.

We had 3 years in the country with sub standard storage rads that never heated the place properly (one big rad and 2 small ones for a 3 bed house) so this year I thought I'd go wild and take advantage of living somewhere with mains gas and put the heating on.

install a combi boiler, quick!

the cost of heating a cylinder of water by gas is in the region of 10p

If the cylinder is well-insulated, it will stay hot enough (unless you use it) for 24 hours or more.

Do you not have a programmer that allows you to set separate times for CH and HW? During the summer it is more economical to run the boiler for HW just before you get up in the morning, and again before people have baths or showers in the evening, because it prevents the boiler frequently firing for short periods to top up the cylinder after every sinkful, but you should be able to do that with the timer.

How is your cylinder, and the hot pipes, insulated?

Renting, have to save money to buy a house.

I ran mine the other morning and timed it and worked out it costs 18p or so to heat for 20mins on our tariff, which is low.

I cant find a jacket to fit it, it has one but the cupboard is still warm and I dont think it's the right size anyway as it has loads of pipes coming out of it for the power shower and theres gaps in it. It's 27inches according to the label on the tank.

If you switch the heating on here the water comes on too but not vice versa.

We dont really need hot water, we have a dishwasher and only take one shower each a day. If I had an electric shower I wouldnt even put the hot water on unless we needed a bath.

You might consider moving the cylinder stat up. It is probably retained by a belt like stretchy net-curtain wire. If you put it one-third down from the top of the cyl it will (should) only heat that much water. You may have to undo the "buckle" to get it past the pipes. Turn the power off at the main switch first as the stat and cable may be live.

A new cylinder jacket is usually about £10. If you can find any on subsidy at £3, buy two. You can overlap them. They are in segments like an orange so will fit odd shapes and sizes.

The pipes ought to be insulated with stiff plastic foam, it is not at all expensive and can be cut with a breadknife. You will probably need 22mm and 15mm unless the heating system is quite old when some pipes may be 28mm

Insulation will pay for itself in a matter of weeks.

The stats on the top, it's fixed to the tank and has electric cable coming out of it.

There is foam on the pipes.

I dont think the LL is concerned about bills etc. Never seen so many high energy bulbs. Took me ages to replace them all.

Would that jacket fit a tank thats not even waist height? it's a half sized tank.

Ah

Does your thermostat look like this?

Or like the round cap on this but made of black plastic?

The jacket will fit anything, you just tuck it up at the bottom if the cylinder's too short, or use an extra segment from the spare jacket if it's too fat

second one. .

Ah.

That's the top of an electric immersion heater, it is used when the boiler is out of order. It does not affect the boiler. Sadly it will not affect gas usage. The immersion heater has its own thermostat, which shoiuld usually be set at about 55C. Do not insulate over the cap.

It sounds like you have an older heating system, probably with a cast-iron boiler, often an old Potterton, and gravity circulation to the cylinder. The circulation between boiler and cylinder will not be pumped, and will not have an electric valve to stop it when the cylinder comes up to temperature. You might find that the hot water from the taps gets uncomfortably hot during winter when the boiler is on for long periods to heat the radiators.

If you look at the big pipes that go into the or front side of the cylinder, one near the bottom, and one above it, about half-way up, there is a faint chance that you will see a big brass thermostatic valve with a plastic cap, often blue, on it where the lower one joins the cylinder. However these valves are often jammed, and cost over £100 to buy, so not much hope here either.

You will save a bit of energy by turning down the boiler thermostat so that it does not overheat the cylinder, this will also make the rads less hot so you may need to turn it up again in cold weather. Otherwise, insulate the cylinder with as many jackets as you can get round it, and the hot pipes, especially the big ones between the cylinder and the boiler.