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Hot water not very hot

(31 Posts)
wooooofudge Sun 30-Oct-16 09:44:56

We have an Ideal Mexico floorstanding boiler which must be 30 years or so old and the hot water tank in the bathroom cupboard is orange/yellow. It's about 4 ft tall.

The heating is working fine, but the hot water is just warm. We switched both the water and the heating off at the wall control when we went away for a fortnight, but we've been back since Friday night now and even though I put the water on for several hours yesterday, in case it needed longer than the programmed couple of hours evening and morning to heat the tank from completely cold, it's still not hot.

Any ideas or suggestions how to resolve this? I'm not familiar with hot water tanks having lived in houses with combi boilers for about thirty years. I don't know how to set the water temp - it was good and hot before we went away though.

wooooofudge Sun 30-Oct-16 13:19:37

Bump - calling PigletJohn or anyone who can help!

Lunde Sun 30-Oct-16 13:32:28

Have you checked the thermostat? Is it possible the water temp was accidently turned down when you went away?

wooooofudge Sun 30-Oct-16 14:55:46

There are thermostats for the heating, which are all as they were before we went, but I haven't seen/can't find anything for the water.

timeforachangeithink Sun 30-Oct-16 15:01:41

Your thermostat will control both. Turn it up and use the radiator individual thermostats to turn them down if necessary.

RockyRoadster Sun 30-Oct-16 15:09:01

Not necessarily, I've got a thermostat for the hot water on the outside of my hot water tank

wooooofudge Sun 30-Oct-16 15:54:07

timeforachange I can't see how that would change the hot water temp as everything is exactly as it was before we went away. Having had a look on the web, I'm wondering whether there could be an airlock?

DustOffYourHighestHopes Sun 30-Oct-16 18:54:06

Check the thermostat on the outside of your boiler.

iMatter Sun 30-Oct-16 19:10:56

We have a thermostat on the side of our tank. It's in the airing cupboard and I nudged it when I was putting towels away. Water was bloody boiling.

wooooofudge Sun 30-Oct-16 19:45:18

Boiler is in its own cupboard - we rarely go in there and nothing is stored in there - and the dial on that, which I looked at this afternoon is set to 4, approx flow 71°. It is unchanged, hasn't been knocked or altered.

With the heating on and the immersion heater switched to on (not sure the immersion is actually working as the light to the switch doesn't come on despite replacing the fuse today) the water is significantly hotter.

PigletJohn Sun 30-Oct-16 21:03:30

Use the timer, or the wall thermostat, (not the radiator knobs) to turn the CH off, and let the radiators go cold. Now turn the HW on at the timer. Does the boiler start? Do any of the radiators get warm?

Please photograph the cylinder stat, the wall stat, and the pipework around the boiler and the cylinder.

Look for the pump and especially a 3-port valve which I expect you have got and is probably the source of the problem.

Post your photos.

PigletJohn Sun 30-Oct-16 21:05:03


...with the immersion heater off.

wooooofudge Sun 30-Oct-16 23:08:05

Thank you PJ. Radiators still warm. Will get photos taken. Immersion is off.

wooooofudge Sun 30-Oct-16 23:20:46

Okay - wall stat. There are three of these on different floors. They are not all set to the same temp. GF is set higher. This is the first floor one where both the boiler and hot water tank are situated.

wooooofudge Sun 30-Oct-16 23:24:29

Boiler showing setting and pipework around it. It is possible to isolate each of the three floors with central heating. The hot water in the attic is not supplied by the boiler - there is another immersion heater. Also pic of the pump.

wooooofudge Sun 30-Oct-16 23:26:29

Hot water cylinder pics.

PigletJohn Sun 30-Oct-16 23:59:40

An interesting accumulation of pipework.

First point is that you have sooty black marks on the wall around the boiler. There is a chance that it is just dust shadowing from the uninsulated pipes, but you need to have it professionally inspected in case there is leakage of flue gases.

Second point, the cylinder stat is too high. It must always be lower than the boiler temp. Try it on 60C

Third point, you have numerous 2-port valves. I expect there is one each for each floor's radiators, and for the cylinders. The markings will probably identify them. When all the CH is turned off by timer or wall stats, all the valves feeding radiators should go cold. If one or more heats up when you turn on the HW, there is a fault. Might be a worn-out valve but could be wiring or stat.

Additionally, the pump, which looks like a recent replacement, has been incorrectly fitted sloping. It should be horizontal along the spindle, with the maker's label upright.

wooooofudge Mon 31-Oct-16 07:08:52

Thank you for this - much appreciated. DP turned the cylinder temp up yesterday. I will turn it down.

I can check the valves and whether boiler kicks in when just the HW is turned on tonight when I get in from work with everything cold.

You are right about the two port valves and each floor's radiators. We discovered this after we moved in and had no heating on the first floor.

Coughingchildren5 Mon 31-Oct-16 09:45:58

When I have had this problem it has been due to air in the system.

PigletJohn Mon 31-Oct-16 10:53:11

btw, a modern cylinder with a modern boiler can notionally go from cold to hot in 20 minutes (in reality, the boiler's energy saving controls usually slow it down) but a yellow-insulated cylinder is somewhere around 30 years old, fitting your description, and much slower to heat as it has a smaller coil inside, and loses heat faster, due to the thinner insulation.

If your programmer permits it, set the HW timer to start an hour before the CH starts. Then the boiler can have a good go at heating the cylinder before the radiators start to take heat. You can improve HW by adding extra insulation to the cylinder using a red jacket, and by insulating the hot pipes, especially around the boiler and cylinder, and the pipes between them. A yellow-foamed cylinder might be approaching end of life by now, so if it starts leaking or is too small, consider replacing it with a large modern unvented cylinder. You can get one that will hold more, heat faster, be better insulated and have other advantages that we can look at later. You should only need to use the (more expensive) immersion heater when the boiler breaks down.

The design of your system, controlling each floor and cylinder as a zone, is good, although the pipework and cables around the boiler are not very tidy. By updating the thermostats on each floor, you can programme the heating times and temperatures much better, which will improve comfort and economy. It is quite a simple job, as they swap into the wires for the old thermostats.

I do urge you to get those suspicious black sooty marks looked at. Flue gas leaks are dangerous.

wooooofudge Mon 31-Oct-16 12:09:15

Thanks again PJ. I note your comments about flue gases and we do have a CO alarm located just outside the boiler room/cupboard and will have it serviced and the necessary repair carried out asap. Is it permitted to have both boiler and cylinder in the same place? I'm not sure there's enough space, but it could be a solution.

Thanks for the tip about heating the water first - the BG programmer allows this.

We plan to knock the separate WC and bathroom into one next year and the cylinder is in the airing cupboard which is between the two currently. Consequently we are thinking of relocating it so that could be the perfect time to replace it with a new, better one.

PigletJohn Mon 31-Oct-16 12:30:56

It's OK to put cylinder and boiler together. A new cylinder will be very heavy, so it is often convenient to put it on the ground floor. Typically contain 250l of water (=250kg) and quite tall. Will need to be accessible for maintenance and inspection. To get the best out of it you'll need high water flow so maybe a 22mm pipe to your stopcock, and in some cases a new waterpipe out to the pavement.

Due to very good insulation they do not give out much waste heat in the airing cupboard. Your boiler and pipes may give out more.

wooooofudge Mon 31-Oct-16 13:01:57

Hmm - we have old lead pipes into the house and shared mains supply with next door although I think there are grants available for replacement (Edwardian house which was extended and then split in 1920s). We have a ground floor location for a new cylinder which in terms of pipework, etc wouldn't be too disruptive. Is it okay to locate one near a consumer unit?

PigletJohn Mon 31-Oct-16 14:24:30

yes, but cables must be separated from hot objects such as heating pipes.

Ask the water co to test your drinking water for lead content (they can be slow to arrange it, and the test must be done before you start work).

A lead pipe is overdue for renewal anyway, it could start leaking at any time. If you upgrade to an unvented plumbing system, you are very likely to need a new supply pipe out to the pavement, in 25mm or 32mm plastic pipe. The material is cheap, but it is wearisome to dig a trench. The water co might connect the new pipe for you at a reduced price if you qualify for lead replacement. However you can use an unvented cylinder off your old water tank until/unless you change the supply pipe. You will not get the full benefits though.

wooooofudge Mon 31-Oct-16 18:46:12

Me again - putting the hot water on on its own doesn't make the boiler fire up, only the central heating does. Come to think of it, if you ran a bath, you could hear the water running into the cylinder as you drew water out. I can't hear this happening now.

This is the control for both and I've checked the programming and it's all okay.

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