no hot water when radiators are on

[pwdevon]

Hi
I had taken out a protection pack with my bank which is supposed to protect my gas boiler. This is done through the AA.

I called them out because when heating is on i get very little hot water when i turn the heating off the hot water comes through lovely.

After some testing the engineer said it was the heat Exchanger that was partially blocked. He determined this by doing a calculation of the heat temp going was higher than the heat temp coming out. Because the difference was 19oc this would not be covered by the insurance.
He said the "operation of the diverter assembly all appears correct"

Now i have no knowledge of a working boiler so my question really is : if when the heating is working and i get rush of hot water then constant cold from the tap. When i turn the heating of at the thermostat and put the hot water back on I get lovely hot water my thoughts would lead to the operation of the diverter?

Any help would be great, as i don't really want to pay nearly £300 to an insurance policy that is supposed to give me "peace of mind".

Thanks

 

[45yearsagasman]

Aaahhhh " the boiler". I wonder what the make/ model is. I guess we will have to ask!
Sorry to be sarcastic, but so many people post with little or no relevant info.

 

[JohnD]

It's a white one.

 

[pwdevon]

sorry guys its an ideal isar HE 30
It is white with a lovely grey cover!

 

[muggles]

So you've got an insurance policy that requires you to pay extra in the event that you need to make a claim? Sounds like a massive con to me...

Could be the diverter valve, let the heating go cold then turn on a hot tap and feel the heating flow pipe. If it starts getting warm then the DV is stuck

 

[pwdevon]

Hi Muggles

i let everything go cold i turn on a hot water tap got nice hot water so filled the bath!
i then turned the heating on and still hot water filling the bath but no heating.

turned off tap but no heating. turned boiler off and on heat came on i then tried the tap at first came out hot but then went to luke warm and stayed there.
generally i put the heating on first then when i use the tap i get a little spurt of hot water then it goes cold.

the engineer said it was the heat exchanger that was partially blocked and because this can be maintained then they won't pay for the repair

 

[45yearsagasman]

Firstly, a combi will either do HW or CH not both together. That said it does sound like the diverter is sticking(quite common on this model) This is easily repaired by fitting a new cartridge in the diverter valve.

The AA should stick to cars and leave boilers to experts.

 

[Dean744PiN5]

all boiler cover policies are the same, sludge and limescale related issues are not covered. It is always in the small print that people neglect to read and then moan when they find they are not covered.

The reason being is that it is seen as an avoidable situation and not just general wear and tear.

Not saying it's right or wrong, it's just the way it is.

imo the policy companies should make it crystal clear what is and isn't covered and should actively encourage consumers to have an ongoing water quality maintenance plan to avoid these situations from even happening.

 

[muggles]

You haven't done as I suggested as far as I can tell so we're no further forward...

 

[TeaTime]

You haven't done as I suggested as far as I can tell so we're no further forward...

Lol, my thoughts exactly.

Forget about the policy and the hot water temperature, check if the DV is stuck feeding your heating system, as muggles suggested.

 

[pwdevon]

Firstly, a combi will either do HW or CH not both together. That said it does sound like the diverter is sticking(quite common on this model) This is easily repaired by fitting a new cartridge in the diverter valve.

The AA should stick to cars and leave boilers to experts.

Thanks for the reply.

so my understanding of the heat exchanger is that the unit itself is in water which heats up when on demand. Water travels through the exchanger heats up and goes to either the hot water tap or heating which ever is required. so even it was partially blocked the water coming through would still be hot as it is staying in the exchanger staying warm..then the diverter simply switches to what ever demand is required hot water or heat?

sorry for the quick boiler lesson but i like to get an understanding for when i have chat to the AA

 

[TeaTime]

Firstly, a combi will either do HW or CH not both together. That said it does sound like the diverter is sticking(quite common on this model) This is easily repaired by fitting a new cartridge in the diverter valve.

The AA should stick to cars and leave boilers to experts.

Thanks for the reply.

so my understanding of the heat exchanger is that the unit itself is in water which heats up when on demand. Water travels through the exchanger heats up and goes to either the hot water tap or heating which ever is required. so even it was partially blocked the water coming through would still be hot as it is staying in the exchanger staying warm..then the diverter simply switches to what ever demand is required hot water or heat?

sorry for the quick boiler lesson but i like to get an understanding for when i have chat to the AA

That's pretty much it, on a simple combi system. Now, if you do as muggles has suggested in his first post, you will be able to tell if the diverter valve (DV) is stuck, meaning that it is only feeding the central heating system. If you can confirm this or negate it, we will be able to offer a little more advise.

 

[pwdevon]

OK

I am presuming the heat flow pipe is the one with the pressure gauge on it.

boiler off all pipes cold
Turned boiler on withe thermostat turned right down the heat flow pipe went warm.
Waited to see if this would cool, but kind of stay around the same temp.
Turned on hot water tap nice hot water. Checked heat pipe this stayed at the same warm temp it was. Pipe next to it hot presume(hot water out)

 

[TeaTime]

OK

I am presuming the heat flow pipe is the one with the pressure gauge on it.

boiler off all pipes cold
Turned boiler on withe thermostat turned right down the heat flow pipe went warm.
Waited to see if this would cool, but kind of stay around the same temp.
Turned on hot water tap nice hot water. Checked heat pipe this stayed at the same warm temp it was. Pipe next to it hot presume(hot water out)

On your boiler, the central heating (CH) flow should be the very far left pipe as it exits the boiler.
The next one in is the domestic hot water (DHW) out.

If you are putting demand on the hot water and not getting it, but you are getting a decent service from the CH flow, I guess the diverter valve is in need of maintenance or replacement

 

[pwdevon]

Thanks to everyone who has given advice
I have had a local plumber round who believes the problem is the diverter valve, so i will be have a chat with the insurance company.

thanks again

Paul