No hot water - but boiler working.

[gerbils]

I am getting heating in my rads but no hot water - boiler fires fine and pipes get super hot, but not the one to the tank. Red lines = hot pipes.

My 3 way valve has a lever that has no resistance when off - which suggests that's the fault? Happy to fit a new motor but wondered if it may be anything else?

 

[stem]

The 3 port valve maybe sticking, especially if it has only recently been brought back into use with the heating. However, normally when they fail they revert to the hot water position and give hot water only and no heating.

First switch both the heating and hot water off and now move the lever, you should feel some resistance now. If you still don't feel any resistance, the valve is probably sticking in the heating position. Make sure the lever is free to move and not latched in the 'Man' position.

If there is some resistance, The valve would appear to be working. It's possible that there maybe a problem with the hot water cylinder thermostat, in that it is not calling for heat, so the diverter valve is not directing any water to the hot water cylinder. If you are electrically competent, have, and can use a multimeter the switching functions can be easily checked.

 

[gerbils]

Hi Stem,

I have no resistance in the switch when everything is off.
I have no resistance in the switch when the heating is on.

But I do have resistance in the switch when the water is on - it resists me putting it in manual mode and springs back up.

 

[oilboffin]

It will hook into a slot for a temporay fix

 

[stem]

I have no resistance in the switch when everything is off.

OK, that is normal, if the heating was the last thing to be 'on' then the valve will stay in the heating position and there will be no resistance.

I have no resistance in the switch when the heating is on.

Also OK. The motor has wound the valve to the heating position already and so the lever will be loose and not do anything.

But I do have resistance in the switch when the water is on - it resists me putting it in manual mode and springs back up.

Then that is also as it should be and means the valve is actually in the hot water position. It is pulled there by a spring and this is when you feel the resistance.

Now, make sure that the heating and the hot water are both switched off and then put only the hot water 'on' check that you can feel the resistance of the valve spring as before. This means that the valve is actually in the hot water position, but, does the boiler come on?

I'm assuming here that the water in the hot water cylinder isn't hot.

 

[gerbils]

OK, that is normal, if the heating was the last thing to be 'on' then the valve will stay in the heating position and there will be no resistance.

Also OK. The motor has wound the valve to the heating position already and so the lever will be loose and not do anything.

Then that is also as it should be and it is actually in the hot water position. It is pulled there by a spring and this is when you feel the resistance.

Now, make sure that the heating and the hot water are both switched off and then put only the hot water 'on' check that you can feel the resistance of the valve spring as before. This means that the valve is actually in the hot water position, but, does the boiler come on?

I'm assuming here that the water in the hot water cylinder isn't hot.

OK - if I put hot water on (via my hive system) I can hear the 3 way valve engage, the boiler goes on, I feel resistance putting the 3 way into manual, but I get no hot water.

 

[stem]

Has anything else changed recently? Any gate valves adjusted? Wiring altered? Is the pipe from the motorised valve to the cylinder hot or cold?

 

[gerbils]

Well, I am unsure how long this has been an issue because, and I'm embarrassed to say, we only just noticed hidden in the airing cupboard is an emersion switch that has been set to 'on' all this time (not lived here that long, but long enough I should have known this). So unbeknown to us, each time the boiler programme kicked in to heat the hot water I mistakenly assumed this was heating the water...

Apart from that - some months ago we had a plumber round who turned off the valve above the pump and didn't turn it back on again so when we ran the heating it made a right horrible noise until I turned it back on...

 

[stem]

Is the pipe going from the motorised valve to the cylinder hot or cold when the hot water is switched on? If the hot water cylinder is cold it will take some time for the boiler to heat it up to a point where hot water gets to the taps.

It maybe that you have a plumbing issue, rather than an electrical / control issue. On the return pipe from the hot water cylinder (the one in front of skirting) there is a valve, if this valve has been closed at some point, then that will stop water from the boiler flowing through the cylinder.

If the immersion has been keeping the cylinder full of hot water, then the thermostat wired to the motorised valve won't switch the boiler on, but it sounds like this isn't the case now and that the boiler is coming on.

 

[gerbils]

Is the pipe going from the motorised valve to the cylinder hot or cold when the hot water is switched on? If the hot water cylinder is cold it will take some time for the boiler to heat it up to a point where hot water gets to the taps.

It maybe that you have a plumbing issue, rather than an electrical / control issue. On the return pipe from the hot water cylinder (the one in front of skirting) there is a valve, if this valve has been closed at some point, then that will stop water from the boiler flowing through the cylinder.

If the immersion has been keeping the cylinder full of hot water, then the thermostat wired to the motorised valve won't switch the boiler on, but it sounds like this isn't the case now and that the boiler is coming on.

The pipe running from the motorised valve doesn't get hot when the hot water & boiler are running - to be precise the pipe at the valve end does get hot but it's progressively colder as you go towards the tank.

We've only ever run the hot water via a programmer, twice a day for X months and the boiler always came on during this time. It was only when I switched the immersion off and realised we had no hot water that I twigged there was an issue...

 

[Hot&Cold]

Has anything else changed recently? Any gate valves adjusted? Wiring altered?

Very good question from stem,all info helps,original post from gerbils in May but there was no reply from gerbills and little help could be offered.feedback https://www.diynot.com/diy/threads/no-hot-water.482441/

Well, I am unsure how long this has been an issue because, and I'm embarrassed to say, we only just noticed hidden in the airing cupboard is an emersion switch that has been set to 'on' all this time

This is a very basic fault to sort out even with diy fitting of wifi thermostats but the original installation/fittings has to be correct before moving forward.

It looks like your enquiry in May received a reply but you offered zero feedback ,if you dont reply no fooker will care and assume its all sorted.

 

[gerbils]

Very good question from stem,all info helps,original post from gerbils in May but there was no reply from gerbills and little help could be offered.feedback https://www.diynot.com/diy/threads/no-hot-water.482441/



This is a very basic fault to sort out even with diy fitting of wifi thermostats but the original installation/fittings has to be correct before moving forward.

It looks like your enquiry in May received a reply but you offered zero feedback ,if you dont reply no fooker will care and assume its all sorted.

Thanks, appreciate that. Yes I have no way of knowing if the original wifi fitting is correct or not. Given past experiences, I think possibly not!

 

[Hot&Cold]

I have no way of knowing if the original wifi fitting is correct or not. Given past experiences, I think possibly not!

Thats fair enough,info is the key here. plumbing=Your 3 port valve could be defective,the cylinder coil could be blocked or the balancing valve blocked/shut. Its important to prove coil circulation.

Electrics,a photo of what you have adjacent to your cylinder and a couple clear photos inside the wiring center,take time to isolate power and move wires around for a few photos.

Its diy fixable as long as the plumbing is clear.

 

[stem]

I would start with checking the balancing valve in the pipe parallel to the skirting. Open it up fully, but count how many turns it takes, so that you can put it back afterwards. Then just turn on the hot water and see what happens. The hot water cylinder would need to be cool first though otherwise the cylinder thermostat might not fire up the boiler.

Your description of the operation of the valve is exactly what a correctly operating valve would do, so unless it's blocked internally somewhere I don't think you have a valve or wiring fault, everything seems to be 'positioning' as it should.