Hot water: TOO HOT. Cold water: only from taps

Janderclander · 27 Sep 2007

Hello everyone. My first post here.

A week ago I came back from holidays and found the following situation:

Hot water was extremely hot, while there was no cold water from the two showers (also really hot) but it was fine from the kitchen and bathroom taps.

Also, the loft was covered in water and it has even gone downstairs through one wall, ruining the paint.

My house is about ten years old and my central heating systems consists of:
A big tank and a small one in the loft
An electric water heater cylinder in the bathroom
A gas boiler in the kitchen.

I have now switched off the electric heater and things are back to normal. I am using just the downstairs gas boiler for everything, but I have to remember to turn on the heater 30 minutes before I need a shower, which is annoying.

My first guess is that the thermostat (Drayton HTS3) of the electric boiler is gone and it just works all the time. Am I right? What else can cause the heater not switching off?

I would also like to know how the system works, the point in having a gas and electric heaters as well as the two tanks in the loft and why there was water in the loft (condensation?). How can there be cold water from taps but not from any showers?

Hope someone can help
Many thanks inadvance.

Agile · 27 Sep 2007

Sounds as if you left the immersion element on and the stat has failed.

There is apparently a fault causing the gas boiler not to heat the cylinder.

You either need somebody competent or to investigate the control system whatever that is.

Tony

Janderclander · 27 Sep 2007

Hello Agile

The electric heater with the inmersion element is always on, but I believe the thermostat should switch it off when the water reaches certain temperature. I have been living here for over a year and never switched it off. Maybe I should when I go on holidays, but still, the thermostat should control it.

That is why I guess that component, HTS3, is the problem.

What do you mean by "There is apparently a fault causing the gas boiler not to heat the cylinder."? My problem is the water is too hot, so I don't think there is a fault with heating anything up

JohnD · 27 Sep 2007

Janderclander said:
I have been living here for over a year and never switched it off.

I'm glad I don't pay your electricity bills

Janderclander · 27 Sep 2007

They are not too bad

What I thought is: The gas boiler heats up the water and sends it to the immersion tank in the bathroom, which maintains the temperature at 50 or 60 or whatever you set on the thermostat. Something is wrong there because if I switch this electric thing on, water is at over 200 degrees at least. I have now switched it off and still have hot water and central heating, but not instantaneously as before, probably because the water is not being kept hot in that tank after switching it off. Am I wrong?
How do the gas and electric heater work together?

JohnD · 27 Sep 2007

can you post a picture of the cylinder and all the pipes around it?

what does "not instantaneously" mean? A bucketful, a bathful, a minute, twenty minutes?

when you say 200 degrees, you mean fahrenheit, right? not celsius? have you measured it with a thermometer, or is that a guess?

Janderclander · 27 Sep 2007

Well, maybe I exaggerated the 200 degrees thing, but if I left the water from the shower running, in a few minutes there is fog all over the house and you can barely touch the water. As i said, it is all ok now I switched the electric heater off.

Problem is, I don't understand how the system works.
I always had the gas boiler set to OFF for both heating and water, unless I wanted to use the radiators, so I would program them for a couple of hours lets say, but the HW setting was always off. Then I had the cylinder always on, with the thermostat that has attached to it set to 55 degrees. And everything was fine for a year until last week when the hot water went mental.

So maybe I should do the opposite? Switch the cylinder off and keep the Gas Boiler HW setting to ON all the time? Or program it to be on for a couple of hours twice a day? I only set the timer for the CH, not the hot water. Maybe that is why now, when I need hot water it takes about 20 minutes after I set the gas boiler to HW for it to deliver, because the hot water tank is just cold once the electric heater is not working anymore.

Someone please explain to me what settings to use

and maybe why things went wrong all of a sudden with my old (probably wrong and expensive) setup

JohnD · 27 Sep 2007

JohnD said:
can you post a picture of the cylinder and all the pipes around it?

still asking

//www.diynot.com/forums/viewtopic.php?t=99672

Janderclander · 27 Sep 2007

Hi JohnD.
Many thanks for your replies.
I have edited my previous post explaining wh I thinkk the hot water takes a while.
I will post pictures when I go back home, but for now, can you please check that post again and see if you know what the right setup would be? Electric always off and HW on boiler always on?

EDIT: I might be able to post the photos in a few minutes. Just asked someone at home to take them and send them to me.

JohnD · 27 Sep 2007

quite likely

gas is half the price of electricity but the immersion is useful in summer or when your boiler breaks down or is being serviced

the cylinder should have foam insulation or a red fibreglass jacket.

your boiler should have a timer on it. Set it to turn on the hot water 20 minutes before you get up in the morning, and 20 minutes before you come home at night. Let it turn off when you leave the house or go to bed.

A modern gas boiler will heat a modern cylinder from cold to hot in 20 minutes.

your immersion thermostat has probably failed and needs to be changed.

we still need to see the picture

Agile · 27 Sep 2007

"""Sounds as if you left the immersion element on and the stat has failed.

There is apparently a fault causing the gas boiler not to heat the cylinder.

You either need somebody competent or to investigate the control system whatever that is."""

I told you this because thats what I conclude is your problem. However you chose to tell me that you think differently.

As a professional in the heating industry its quite likely that I am right.

You clearly have little idea how your system operates and choose to operate in a very expensive way as well.

If you dont want to listen to good advice then I suggest that you should not ask for it.

Tony

TicklyT · 27 Sep 2007

Normally, day to day hot water requirements would be supplied by the gas boiler. The immersion heater would only be used as a backup if the boiler had failed, or was going to be left turned off for an extended period, say, during the summer.

If the 'stat on the immersion heater was set higher than the boiler 'stat, and the immersion heater left on, then the immersion may take over heating the water from the boiler entirely. The boiler would shut down, and play no further part as it's thermostat sees the water as hot enough already.

If either 'stat has failed, along with any other safety cutouts that may or may not be fitted, and left to it's own devices, the system may start to drive a thermosyphon through the hot cylinder vent pipe back into the cold storage tank like a big coffee percolator, heating the cold water as the whole system approaches boiling point. This would explain the lack of cold water at the showers and the condensation in the loft.
The system would now be a potential bomb. The only 'control' left on the system is manual intervention (running off some hot water or turning off the boiler or immersion heater)

JohnD · 27 Sep 2007

Agile said:
Sounds as if you left the immersion element on and the stat has failed.

There is apparently a fault causing the gas boiler not to heat the cylinder.

You either need somebody competent or to investigate the control system whatever that is.

Tony

I completely agree with Agile although the "fault" was with the user

Janderclander · 27 Sep 2007

Here is one:

You can see the tank, the themorstat, the three way valve and a pump. Also the switch I have now turned off.
The red handle between the pump and the 3-way valve, can you guess what it is for?. Not sure if I messed with it and if it should be closed or open.[/img]

Janderclander · 27 Sep 2007

Hi Tony.

I am really sorry you got wrong the tone of my reply. I am not dismissing your suggestion at all. Just did not understand what you meant and asked why you thought there was a problem with something not heating something else when my problem was there is too much heating

, as that is what I understood from your answer. Obviously I have not got a clue how this thing works and did not understand your reply either.

It was definitely not the way I intended to answer. Sorry I made it look a different way.

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Hot water: TOO HOT. Cold water: only from taps

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