Boiler does not turn on for hot water

debitcardmayhem

Is that tank heaten by an immersion heater (it say heater on the outer label)?

QrizB

robshak said:

How much fault-finding are you prepared to do? Would you like us to talk you through it?

That is some really good information. Thank you. There seems to be a lot to learn.
I am definitely into fault finding. It would indeed be very helpful if you could talk me through what I should do?

When you've got half an hour to spare and the weather isn't ridiculously warm ...

Advance both heating and hot water on the controller. Make sure the room thermostat is turned up to max. Your boiler should kick into life. Give it 5 minutes to warm up.

Go to your three-way valve. Check that the valve actuator is in the middle.

One of the ways will be the input, one will feed the heating and one the hot water cylinder. All three should be equally hot. Touch them carefully (they're hot!), ideally 100mm or so away from the valve, and confirm this.

FreeBear

robshak said:

One comment - 30KW boiler just for central heating and a hot water tank !!! You probably only need ~14KW unless you have a mansion to keep warm.

Ha ha..not really a mansion (4bed approx 200sqm) but the previous owner did some upgrades..yes 30kw hits the pocket hard when the heating has to go on..

Whilst it is possible to use a combi boiler as a heat only (system) boiler, it is unusual. But being a fairly new one, it should be able to modulate down, and in doing so, reduce the amount of gas it burns. The manual should give you the specs on minimum heat output and gas consumption figures. If you haven't got a manual and/or can't find a copy on line, post the model & serial number and we can go digging.

If this boiler does support modulation, it would be worthwhile fitting a smart(er) programmable thermostat - It could save 10-15% on your gas consumption. Screwfix currently have Drayton Wiser and Tado two channel thermostats on offer at £99 each - Check for compatibility with the WB boiler as they use a proprietary interface. 

robshak

Ectophile said:

robshak said:

One comment - 30KW boiler just for central heating and a hot water tank !!! You probably only need ~14KW unless you have a mansion to keep warm.

Ha ha..not really a mansion (4bed approx 200sqm) but the previous owner did some upgrades..yes 30kw hits the pocket hard when the heating has to go on..thanks for the advice on electric connection..will shut if off at mains and check..any way to identify if it is blown?

Do you normally leave the boiler's central heating temperature set to maximum?  If so, that won't be helping your gas bills.

No, that was just me trying everything to see if the boiler would kick in for hot water.

robshak

FreeBear said:

robshak said:

One comment - 30KW boiler just for central heating and a hot water tank !!! You probably only need ~14KW unless you have a mansion to keep warm.

Ha ha..not really a mansion (4bed approx 200sqm) but the previous owner did some upgrades..yes 30kw hits the pocket hard when the heating has to go on..

Whilst it is possible to use a combi boiler as a heat only (system) boiler, it is unusual. But being a fairly new one, it should be able to modulate down, and in doing so, reduce the amount of gas it burns. The manual should give you the specs on minimum heat output and gas consumption figures. If you haven't got a manual and/or can't find a copy on line, post the model & serial number and we can go digging.

If this boiler does support modulation, it would be worthwhile fitting a smart(er) programmable thermostat - It could save 10-15% on your gas consumption. Screwfix currently have Drayton Wiser and Tado two channel thermostats on offer at £99 each - Check for compatibility with the WB boiler as they use a proprietary interface. 

I will do some learning onodulation, check for capability of my boiler, look for manual and if I cannot find it, come back to you as you have kindly offered. Thanks again.

robshak

debitcardmayhem said:

Is that tank heaten by an immersion heater (it say heater on the outer label)?

Yes, there is an immersion heater inside the hot water tank..I found out when I flicked an unidentified switch in landing and my electricity bill went up the roof. See my previous thread on it :-)

robshak

QrizB said:

robshak said:

How much fault-finding are you prepared to do? Would you like us to talk you through it?

That is some really good information. Thank you. There seems to be a lot to learn.
I am definitely into fault finding. It would indeed be very helpful if you could talk me through what I should do?

When you've got half an hour to spare and the weather isn't ridiculously warm ...

Advance both heating and hot water on the controller. Make sure the room thermostat is turned up to max. Your boiler should kick into life. Give it 5 minutes to warm up.

Go to your three-way valve. Check that the valve actuator is in the middle.

One of the ways will be the input, one will feed the heating and one the hot water cylinder. All three should be equally hot. Touch them carefully (they're hot!), ideally 100mm or so away from the valve, and confirm this.

OK, did all of above. The boiler kicked in. Hot water is feeding CH but not getting into hw tank. So had to manually flick switch at position 1. Then hot water went into tank and is ONLY coming out of tank at point 2.

The tap has mild warm water, not even sure if it is from the hw tank or the temperature outside..ha ha..

As soon as the programmer for CH turned off at controller, the boiler shut down.

Where is the three way valve and actuator located inside the boiler?

QrizB

robshak said:

OK, did all of above. The boiler kicked in. Hot water is feeding CH but not getting into hw tank. So had to manually flick switch at position 1. Then hot water went into tank and is ONLY coming out of tank at point 2.

That's good, as expected.

robshak said:
As soon as the programmer for CH turned off at controller, the boiler shut down.

If the programmer was still set to demand HW, that's less good.

It makes me think that the tank isn't calling for heat. Possibly a faulty tank thermostat?

If you choose to bail out and call a professional at this point, we won't judge you!

------

The manual for your tank is here:
https://osohotwater.co.uk/wp-content/uploads/2021/10/Manual-20-series-RI-production-dates-2000-2010.pdf

From the diagram on page 2, it looks as though the tank thermostat is under the white cover.

Wiring diagrams from page 7. You'll need to know whether you have an S-plan or Y-plan system.

There is likely to be mains voltage under the cover so don't remove it unless you're comfortable working with live electrical equipment.

robshak said:

Where is the three way valve and actuator located inside the boiler?

Your silver box at position 1 is the control valve for hot water.

I've been assuming it's a three-way valve but it might be two-way. If two-way, there will be another one just like it somewhere to control the heating circuit.

Y-plan heating uses a three-way valve. S-plan uses two (or more) two-way valves.

matt_drummer

robshak said:

OK, did all of above. The boiler kicked in. Hot water is feeding CH but not getting into hw tank. So had to manually flick switch at position 1. Then hot water went into tank and is ONLY coming out of tank at point 2.

The tap has mild warm water, not even sure if it is from the hw tank or the temperature outside..ha ha..

As soon as the programmer for CH turned off at controller, the boiler shut down.

located inside the boiler?

I am not sure if you know how the tank works, forgive me if I am telling you something you already know.

 The boiler does not heat the water in the tank directly.

The tank has a coil of pipe inside it and the hot water from the boiler flows around the coil of pipe inside the tank transferring heat to the water in the tank that ultimately comes out of your hot water taps.

It will take some time to heat the tank, it is not instant like the hot water supply from a combi boiler. I know you have a combi boiler but it is set up as a system boiler.

It does sound like your three way diverter valve is faulty. it is item 1 in your photograph.

That may not be the only problem though.

If your are confident and careful you can remove the motorised head from the valve and make sure that the valve itself is not stuck. 

Be careful though if you do this, there is live mains electricity here so ideally you should isolate the electrical supply.

A new motorised diverter valve head is a cheap and easy fix. If you need to replace the whole valve it is a bit more involved.

There are plenty of videos online to assist you.

matt_drummer

QrizB said:

Your silver box at position 1 is the control valve for hot water.

I've been assuming it's a three-way valve but it might be two-way. If two-way, there will be another one just like it somewhere to control the heating circuit.

Y-plan heating uses a three-way valve. S-plan uses two (or more) two-way valves.

I just looked back at page 1.

It does look like a two way valve.

They should be able to narrow it down to the valve or the thermostat easily.

Turn on just the hot water on the programmer with the heating off and open the valve at 1 manually as they did before.

If the boiler fires it is the valve, if it doesn't then it must be the thermostat?