Can you help please?

[idkwia]

I have been advised by two plumbers but both say different things. I paid one £500 to do some work which was ok but I still have a problem. Can anyone here help me please so I can decide which of these guys is right?

I have a regular boiler which I believe is open flue. I have a thermostat on my cylinder which has just been renewed. I have a newly fitted gas valve. I also have a newly fitted room thermostat.

The CH and water is working etc but the water is much too hot. I have got the cylinder thermostat turned down to about 40 degrees. If I only have the HW on then the cylinder thermostat turns the boiler on and off as it is supposed to do. But when the heating and hot water are both on then the water from the taps is much to hot.

Because of the cold weather I have been leaving the heating on constantly and so overnight I am not using any hot water so wouldn't the water eventually heat up to 80 degrees as per the boiler thermostat anyway, or should the system somehow self regulate? In other words because I am not drawing off any water and because the heating is constantly trying to keep the house warm wouldn't the water just get hotter and hotter until it reaches the 80 degrees as set by the boiler thermostat regardless of what the cylinder thermostat says?

One plumber says that the system is fine and that is just how it works and the other says I need a new diverter valve and/or the wiring on the cylinder thermostat is wrong. Who is right please?

 

[REDSAW]

welcome to the forum,#

what did you pay £500 for?.

 

[idkwia]

welcome to the forum,#

what did you pay £500 for?.

I paid it for supplying and fitting the gas valve, the cylinder thermostat and the room thermostat.

 

[BLOD]

If you have a cylinder thermostat, then that should control the temperature of the water in the cylinder.
If the water temp just keeps getting hotter & hotter (is that what you are saying ?) then you have a problem,possibly with wiring or valve.

 

[idkwia]

If you have a cylinder thermostat, then that should control the temperature of the water in the cylinder.
If the water temp just keeps getting hotter & hotter (is that what you are saying ?) then you have a problem,possibly with wiring or valve.

Thanks a lot for the answer, much appreciated.
Just so that I understand..........I thought the coil in the cylinder is full of water from the central heating system and I thought it was that that heated the water in the cylinder for the hot water taps. So I thought that if the central heating is on all the time it would have no choice other than to keep heating the water until it reached 80 degrees regardless what the cylinder thermostat says. Because if the cylinder thermostat turns off the system at say 40 degrees how can the heating be kept hot?
Where is my thinking wrong please?

 

[REDSAW]

yous thinking wrong because the stat should be set at 65'c not 80, and your heating 70 max.
then theres the fact of thermal loss through the system. at the end of the night you have a tank of hot water around 60'deg.

 

[BLOD]

Yes you are right - the water from the boiler does go through a coil in the cylinder that heats your domestic hot water up.
But when the cylinder thermostat is satisfied (reaches temperature) it turns the boiler off.
If you have only your central heating on the valve should only allow hot water from the boiler to go to the radiators and not into the cylinder coil.

 

[idkwia]

yous thinking wrong because the stat should be set at 65'c not 80, and your heating 70 max.
then theres the fact of thermal loss through the system. at the end of the night you have a tank of hot water around 60'deg.

On my boiler there is a thermostat switch and I can either have High Flow at approx 82 degrees (winter setting) or Low Flow at approx 60 degrees (summer setting).
I have only got the cylinder setting at 40 degrees to see if it is working. The cylinder thermostat is strapped to the tank about a third of the way up. One plumber said it should be higher up the tank and that would sort it out. But I only had the a new tank fitted last year and the plumber located it where it is.
The water from the taps is extremely hot, can't hold my hand under it.

 

[REDSAW]

does the cylinder have a emersion heater on it?

my conclusion is, its all set wrong go with the second plumber.

 

[idkwia]

does the cylinder have a emersion heater on it?

my conclusion is, its all set wrong go with the second plumber.

Yes, the cylinder has an immersion heater which works well. It is turned off at the moment.

The boiler thermostat is set to high flow (winter setting). I can set the thermostat on the cylinder to 60 degrees but the water still gets too hot.

 

[rallen]

You should not be able to hold your hand under 60 C water for too long (without screaming anyway). Do you have a cooking thermometer to do some better tests ?

Typically (well I am no plumber but from what I have seen) there is a water valve somewhere that diverts hot water into the hot water cylinder when it needs it. It could be a 3-way valve or a 2-way valve or a separate pump forming an individual circuit. Otherwise the hot water would be on as a side-effect of the CH and that sounds strange.

Perhaps, on account of you having already paid 500 pounds, you would not be out of line to ask the first plumber, politely, to draw you a diagram of your system for future maintenance. Of course he could say that it is a bog-standard system and why should he bother.

 

[WHPES]

Your cylinder stat is in the correct position. The plumber who said it should be higher up - don't get him back as this is pretty basic stuff to know.

Stick a thermometer under the hot tap - it shouldn't get above 60 degrees. The cylinder must be set at 60-65 degrees to prevent growth of bacteria such as legionella which causes legionnaires disease.

If you want the tap temperature lower, the means of doing this is by fitting a thermostatic mixing valve under the sink

 

[stevetheplumber]

Yes, the cylinder has an immersion heater which works well. It is turned off at the moment.

The boiler thermostat is set to high flow (winter setting). I can set the thermostat on the cylinder to 60 degrees but the water still gets too hot.

then the cylinder stat isnt closing the motorised valve must be wired wrong or the valve of stat is faulty

 

[doitmyself]

Please answer these questions:

Make and Model of boiler?
How many water pipes connected to boiler?
Do you have any motorized valves (boxes attached to the pipework with a cable attached)?
If so, how many and do they have two or three pipes connected?

 

[idkwia]

Please answer these questions:

Make and Model of boiler?
How many water pipes connected to boiler?
Do you have any motorized valves (boxes attached to the pipework with a cable attached)?
If so, how many and do they have two or three pipes connected?

Hi,
Thanks for the questions. Here are the answers:

The boiler is an Ideal Elan CF30
There are 2 pipes connected to the boiler
There is a motorized valve connected to the pipework and there are 3 pipes connected to it.

I hope you can help. Thank you.
PS The water from the taps is way over 60 degrees.

 

[WHPES]

Sounds like a stat, controller or motorised valve problem

 

[payney1974]

I would guess when you have hw and ch on together and the cylinder stat has reached temperature it tells the 3 way valve to close but it doesnt quite shut the valve to hw completely thus still leaving the hot water coil in the cylinder to heat up and eventually heat your hw up to the temp of your radiators. I would advice you to get 3 way changed, but cant be 100 % without seeing job. I dont think there is a problem with your cylinder stat as it works ok on hw only doesnt it?

 

[migoplumber]

as said above stat or motorized valve problem.

as the stat has been replaced - and i assume wired correctly, that leaves motorized valve as the problem.

i also would go with your second plumber.
either the motorized valve is passing, or has a wiring problem.

 

[idkwia]

I would guess when you have hw and ch on together and the cylinder stat has reached temperature it tells the 3 way valve to close but it doesnt quite shut the valve to hw completely thus still leaving the hot water coil in the cylinder to heat up and eventually heat your hw up to the temp of your radiators. I would advice you to get 3 way changed, but cant be 100 % without seeing job. I dont think there is a problem with your cylinder stat as it works ok on hw only doesnt it?

Thanks for your answer. Yes, the cylinder stat works perfectly when only the hot water is on.

Is there any way of testing the 3 way valve to see if it is faulty? Or is the only way to know is by fitting a new one?

Also, how much do you think it would normally be to supply and fit the 3 way valve?

 

[doitmyself]

Thanks for your answer. Yes, the cylinder stat works perfectly when only the hot water is on.

Is there any way of testing the 3 way valve to see if it is faulty?

Yes.

When only hot water is on, only the pipe from motorized valve to the cylinder should get hot. Does the other branch (to radiators also get hot)?
If it does, the valve is sticking in mid position.
If it does not, there is a wiring problem.

If the valve is sticking, you can sometimes free it.

Remove the actuator (that's the metal box on the valve - no water will come out) and you will see the valve spindle.
This should turn easily by hand - about a quarter turn.
If it is stiff, apply a little WD40 or silicon lubricant.
Replace actuator.

If not sticking, there are electrical tests but they depend on connecting and disconnecting wires (with the power off). Are you comfortable doing this?

 

[Plucky]

I havent read all of the replies so I'm sorry if im going over something already repeated. But I think

1. The system is wired incorrectly

2. The 3 port valve is faulty (unable to shut the HW port off)

3 Someone has modified a system and left an old programmer that is intended for use with a system that has Gravity Hot water. i.e.HW is always on with heating

 

[doitmyself]

Someone has modified a system and left an old programmer that is intended for use with a system that has Gravity Hot water. i.e.HW is always on with heating

Didn't think of that possibility.

OP
Make and model of your programmer/timer, please.

 

[idkwia]

Thanks for the answers guys.

The programmer is a Satchwell but I don't know the model number. However I am certain that it hasn't been modified and also the problem I am having is new so the fault must have recently happened.

I don't think the 3 way valve is getting stuck as it is nearly always in the bottom position and occasionally in the mid positon.

When the heating and hot water are on all 3 conections to the 3 way valve are hot. I will check to see what happens when I only have the water on although as I say, it doesn't seem to be sticking.

 

[Blackcatgas]

Thanks for the answers guys.

The programmer is a Satchwell but I don't know the model number. However I am certain that it hasn't been modified and also the problem I am having is new so the fault must have recently happened.

I don't think the 3 way valve is getting stuck as it is nearly always in the bottom position and occasionally in the mid positon.

When the heating and hot water are on all 3 conections to the 3 way valve are hot. I will check to see what happens when I only have the water on although as I say, it doesn't seem to be sticking.

You have a Y plan system, water is heated from the boiler, this goes to the three port valve this either diverts the flow around the radiator pipes to the left, or around to the cylinder coil to the right, if yo swithc on both the hot water and heating the valve opens mid position allowing equal flow to the radiators and the coil in the cylinder, okay so lets ay youve got the hot water and heating switched on at the same time, and youve got the cylinder stat set to 60deg, the cylinder stat should sense when the water is at the correct temp ie 60deg then turn the three way valve to heating only thus stopping the flow around the coil in the cylinder and sending it around the radiators, then when the water temp drops, the stat will sense this and move the valve back into the mid position, the same goes with the room stat, when the room reaches the desired temp the motor will move over to the hot water. If youve just got the hot water switched on and no heating then the cylinder stat will turn off the boiler aswell, the same goes for if youve just got the heating on and no hot water the room stat will turn off the boiler aswell. I think that either the three port is shagged, or more likey the wiring for the new room stat and cylinder stat is wrong.
Has he used a new white honeywell wiring centre for the room stat etc?, could be somthing as simple as not cutting through the correct links inside it.

 

[idkwia]

You have a Y plan system, water is heated from the boiler, this goes to the three port valve this either diverts the flow around the radiator pipes to the left, or around to the cylinder coil to the right, if yo swithc on both the hot water and heating the valve opens mid position allowing equal flow to the radiators and the coil in the cylinder, okay so lets ay youve got the hot water and heating switched on at the same time, and youve got the cylinder stat set to 60deg, the cylinder stat should sense when the water is at the correct temp ie 60deg then turn the three way valve to heating only thus stopping the flow around the coil in the cylinder and sending it around the radiators, then when the water temp drops, the stat will sense this and move the valve back into the mid position, the same goes with the room stat, when the room reaches the desired temp the motor will move over to the hot water. If youve just got the hot water switched on and no heating then the cylinder stat will turn off the boiler aswell, the same goes for if youve just got the heating on and no hot water the room stat will turn off the boiler aswell. I think that either the three port is shagged, or more likey the wiring for the new room stat and cylinder stat is wrong.
Has he used a new white honeywell wiring centre for the room stat etc?, could be somthing as simple as not cutting through the correct links inside it.

Great answer, thanks a lot, now I understand.
Don't suppose you are close to Stevenage are you?

 

[Blackcatgas]

Great answer, thanks a lot, now I understand.
Don't suppose you are close to Stevenage are you?

No worries, Iam from nottingham I get home sick after M1 junction 24.
get the original installer back?, Its only fair that he gets another bite at the cherry, altghough I dont know what the situation is with you and him.
We all get things wrong somtimes, Ive been back to the same job 3 times before each time thinking Id "cracked" the problem only for it to return.