Hot water too hot :-|


It's a Back Boiler
The central heating is fine.
Immersion heater rarely used.
The hot water is set to come on twice a day for an hour each time.
If water is put on for more hot water and left on (oops) it does not boil up, make scary noises or make the feed tank warm/hot.
The cylinder thermostat is a Drayton HTS3
http://www.discountedheating.co.uk/shop/acatalog/aclhts3.gif is in contact with the tank 3/4 of the way down and it set to 60
So there's the info and here's the problem:
The hot water temp is scalding (but not boiling) hot :-| It doesn't matter what temp the thermostat it is set at.
I've googled for an answer, but there are too many answers to do with central heating. So what might be the problem oh helpful ones?
--
Vj



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"Vdkjll" wrote:

On my Baxi Bermuda gas fire with back boiler there is a rotary temperature control knob under the fire, behind the pull-off plate, marked OFF, LOW, 1, 2, 3, 4, HIGH. I have mine set to 2 which gives hot water to taps and rads at 60 to 65 degrees. If you have this temperature control knob, what is yours set at? You seem to have hot water pumping over in the header tank; what speed have you got the pump set at, is it on 3 (high)? The cylinder thermostat position and temperature setting sounds fine to me.
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News Groups wrote:

It is also set to 2

No I don't, this is what I wrote...

The pump is for the central heating. This issue is just for the hot water.

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"Vdkjll" wrote:

I see. On my system the pump circulates hot water between the boiler and hot water cylinder, and between the boiler and the rads.
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What system have you got?
http://content.honeywell.com/uk/homes/systems.htm
And has it ever worked properly or is this a new fault?
Adam
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ARWadsworth wrote:

Baxi Bermuda 57/4m, it's always been like this.
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On Mon, 05 Feb 2007 12:57:56 GMT, "Vdkjll"

Sounds like your boiler has no heat control and is ignoring the set temperature. Hence the thermostat on it has gone?
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EricP wrote:

How do they *GO*? You mean the one on the cylinder? Must be easy enough to replace, if it is that... cost about 8. I'll try that first.
Tzzzt tzzzz but I'll tun the electric TzzZztt off first shall I? Tuesday nights job...
I hope it's not the thermostat on the actual boiler :-( I'll not tackle that one myself!
Thanks Eric
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I think you missed the link above :)
It is not the boiler itself that matters but how it is controlled.
Adam
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ARWadsworth wrote:

Sorry Adam, the C Plan Schematic matches what I have.
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Great, so either the tank stat is failed short circuit or has been bypassed in the wiring centre because it has failed open circuit and someone bypassed it to get hot water.
The temperature on the boiler thermostat setting has no meaning on a working C plan as to the actual temperature of the hot water in the tank. The tank stat decides the hot water temperature.
Test the tank stat works and check it is wired up correctly, the link gives you the circuit diagram. A neon screwdriver will do the job (just) if you do not have a multimeter
I assume that you do have individual control of both HW and CH and that the hot water temperature is the only problem.
HTH
Adam
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ARWadsworth wrote:

Oooooooooh naughty!

What is that for? Is it for the number of rooms/size of house then?

Adam that's very helpful.
The CH temp is controlled by a room thermostat in the hall and that works properly. We don't have any TRVs.
I'll have to wait til Thursday as My bloke has a multimeter. He'll be so pleased that he is joining in again! :-D
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Not if you need a bath

For houses with no room and tank stats

What a shame. They pay for themselves in no time
Adam
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ARWadsworth wrote:

They will in my new house I'm sure, but the new occupants of this place can have the black radiator water experience!
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If you have a motorised valve on the hot water side of the system then I suggest you check that it is not jammed in the open position.
This is not an oncommon problem with 2 & 3 port valves.
If jammed open then the water will continue to heat when the boiler is heating the radiators.
The same would happen if the valve internals are worn, thereby letting by even though it appears to be closed.
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Chas wrote:

That is not the problem I posted.
Vj

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What you are saying then, is that the water temerature is ok when the programmer switches on for the programmed times, but if the hot water is used up and you overide the timer to top up the hot water this is when you have the overheating problem?
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Chas wrote:

No, That wasn't what I was saying.
"If water is put on for more hot water and left on (oops) it does *not* boil up, make scary noises or make the feed tank warm/hot."
That bit was in the *information* section, not the *problem* section, as I knew from reading all the confusing answers on google and in DIY groups, that this information would be required to rule it out in the first instance and therfore help diagnose the real problem.
:-)
Vj
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I understand.

I understand

I understand

This I do not understand. How exactly do you " put water on for more hot water" and leave on. How do you do this?
(oops) it does not boil

I understand.

I understand.

Missing info. What type of programmer/timer is controling the hot water?

I understand.

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Chas wrote:

Usually the water is switched to TIMED for an hour twice a day. If everyone wants a bath that night then one tank full is not enough, so it is switched to ON, and sometimes it is accidentally left switched to ON all night.
In a house with a hot water system like mine, and there is a need for more water, someone shouts, " Put the water on!" They don't shout "Switch the Hot water Timer/controller to the ON position!"
So sorry if it confused you :-)

The programmer/timer controls when the water is heated and not the temperature. However it's a Lifestyle LP241. My coffee maker is a Delonghi DC300 and that isn't causing a problem either.

You can sleep now :-) night night :-)
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