Boiler problem - no heat

[Clariman]

We have just returned from an overnight away to find the boiler at home not working. There was heavy snow here overnight but it is not freezing at the moment.

The heating controls are calling for heat but the boiler has error lights. It is a Potterton Promax 24/2 HE Plus.

Lights are

Lockout LED light - solid red
Boiler On light - Flashing green
Mains on light - Flashing green

The fault finder in the manual says it is a "Dry-Fire" issue. Some of the potential faults are installation related so I can discount them. One was "Is the system full of water". It should be but how would I know? The appropriate manual page is here https://www.manualslib.com/manual/74716 ... =51#manual

I should add that the pressure in the associated red thing looked low so I opened a valve to top it up and could hear the water flowing and see pressure increase.

Any ideas?

Thanks

[Mike4]

The heating controls are calling for heat but the boiler has error lights. It is a Potterton Promax 24/2 HE Plus.

Lights are

Lockout LED light - solid red
Boiler On light - Flashing green
Mains on light - Flashing green

The fault finder in the manual says it is a "Dry-Fire" issue. Some of the potential faults are installation related so I can discount them. One was "Is the system full of water". It should be but how would I know? The appropriate manual page is here https://www.manualslib.com/manual/74716 ... =51#manual

I should add that the pressure in the associated red thing looked low so I opened a valve to top it up and could hear the water flowing and see pressure increase.

Any ideas?

Thanks

I hate to say this, but the Promax is the only boiler which has defeated me despite my best efforts on multiple occasions, such that nowadays I actively swerve attending them. So my best advice is don't spend any money trying to get it fixed unless you have a boiler tech who knows them well. Cut your losses and install something decent.

Having said that it might be worth booking British Gas to come and fix it. They LURVE selling them so they must have developed some expertise in fixing the buggers. ISTR they have a thing where if you sign up for a maintenance plan with them they'll come and fix it for you for no money on the day. Or they used to anyway.

Or if you are hoping to fix it yourself, that dry fire error message means what you'd imagine. The boiler electronics have decided the boiler has no water in it. Vanishingly unlikely. This is exactly the sort of thing with the Promax that leads me to leave them to other, more competent technicians.

(Check it contains water by loosening one of the pipe connections into it. If you get water squirting out, you can be pretty sure it is not 'dry'.

How old is yours, and which exact version/model of Promax is it? There are quite a few different versions.

Edit to add:
Doh, just noticed you said which version in your OP. I blame this wine, necked in a hurry having just got back from Henley fixing a lovely old Potterton Suprima...

[Clariman]

Thanks Mike

I feel your pain with the Promax. You might recall me posting about intermittent problems that lasted for years. We paid a fortune to boiler engineers with no success. Then I remembered that our Home insurance included emergency cover, so used that. A local plumbing company changed the PCB. Bingo. It fixed it and has been problem free for years! I called our Home emergency cover and they have scheduled a call from the same company as last time. Hopefully they might do the same this time. Fingers crossed they can fix it. If not I'd be happy to replace.

[Mike4]

One thing you're probably aware of but I'll mention it as people often aren't....

Your hot water cylinder probably has an electric immersion heater for emergency hot water in the event of gas boiler failure. Turn it ON if you have one!

[csearle]

Turn it ON if you have one!

We'll make n electrician out of you yet! C.

HNY Mike.

[Clariman]

One thing you're probably aware of but I'll mention it as people often aren't....

Your hot water cylinder probably has an electric immersion heater for emergency hot water in the event of gas boiler failure. Turn it ON if you have one!

We have a megaflo tank. Would the immersion be on that? Hopefully we'll have enough hot water in the tank for showers this morning anyway, but a backup would be good.

On the heating front I'm really glad we have an effective gas fire in the living room and a couple of free standing electric radiators as backup.

[Moosehoosenew]

Our megaflo has an immersion back up, if the gas boiler fails, hopefully yours does too.

[Clariman]

Our megaflo has an immersion back up, if the gas boiler fails, hopefully yours does too.

Thanks for this. What model is yours and how do you switch on the immersion backup or does it happen automatically?

Ours is model number CL300HE and I cannot see any buttons or controls that I have access to.

[ReformedCharacter]

Our megaflo has an immersion back up, if the gas boiler fails, hopefully yours does too.

Thanks for this. What model is yours and how do you switch on the immersion backup or does it happen automatically?

Ours is model number CL300HE and I cannot see any buttons or controls that I have access to.

Does this help?

https://cms.esi.info/Media/documents/Heatr_unventedheater_ML.pdf

RC

[Newroad]

Hi Clariman.

Our Megaflo has an immersion heater for backup, but it needs to be connected up (and able to be switched on) for it to work.

You may think this is obvious, but coming back home after a holiday one Christmas with a failed boiler (circuit board as it happens) we found it hadn't been obvious to the original installer. The sparky (brother of the installation plumber) sorted it the next day, but no hot water (and only electrical heating around the house) until then.

Regards, Newroad

[Moosehoosenew]

Ours is a 250i

We gave an electrical switch close to the Megaflowith 2 wires heading to the megaflo. I believe we simply have to turn it on to make the immersion work.

Sorry I cannot be of more help

[Mike4]

One thing you're probably aware of but I'll mention it as people often aren't....

Your hot water cylinder probably has an electric immersion heater for emergency hot water in the event of gas boiler failure. Turn it ON if you have one!

We have a megaflo tank. Would the immersion be on that? Hopefully we'll have enough hot water in the tank for showers this morning anyway, but a backup would be good.

On the heating front I'm really glad we have an effective gas fire in the living room and a couple of free standing electric radiators as backup.

Most MegaFLO models come with immersion heater element factory-fitted. The installer needs to fit a big fat cable connecting it to a wall isolator switch but many don't bother. So if you don't have a second, fat cable going directly to a wall switch, your immersion heater hasn't been wired up.

Quickest fix for this (assuming no wall switch exists for an immersion heater) is to get a metre or two of heat resistant 1.5mm or fatter (technical term) cable and connect one end to the heater element terminals and the other to a 3-pin plug, then plug it in using a 13A extension cable.

[Clariman]

One thing you're probably aware of but I'll mention it as people often aren't....

Your hot water cylinder probably has an electric immersion heater for emergency hot water in the event of gas boiler failure. Turn it ON if you have one!

We have a megaflo tank. Would the immersion be on that? Hopefully we'll have enough hot water in the tank for showers this morning anyway, but a backup would be good.

On the heating front I'm really glad we have an effective gas fire in the living room and a couple of free standing electric radiators as backup.

Most MegaFLO models come with immersion heater element factory-fitted. The installer needs to fit a big fat cable connecting it to a wall isolator switch but many don't bother. So if you don't have a second, fat cable going directly to a wall switch, your immersion heater hasn't been wired up.

Quickest fix for this (assuming no wall switch exists for an immersion heater) is to get a metre or two of heat resistant 1.5mm or fatter (technical term) cable and connect one end to the heater element terminals and the other to a 3-pin plug, then plug it in using a 13A extension cable.

Thanks everyone. There are 2 thick white cables coming from the panel at the bottom but goodness knows where they go. The boiler is in the garage and the cables disappear into the wall and I don't know where they re-emerge

We used to have a hot water programmable controller in the utility room which backs on to the garage but that was decommissioned when we had the Hive installed. How would I know if the hot water is heated by the boiler or the megaflo? I'd always assumed it was the boiler but maybe not???

[csearle]

There are 2 thick white cables coming from the panel at the bottom but goodness knows where they go.

Well they will emerge from a wall somewhere, possibly into an accessory directly.

If the fuseboard has a circuit labelled water heater or immersion heater then one of the white cables should normally lead to a chunky switch, a fuse-connection unit, or a timer. This might be in the utility room rather than the garage.

Only speculation of course, but the white immersion supply cable will rarely go back to the fuseboard diectly. C.

[Dod101]

I have a Heatrae Sadia Megaflo tank (very big, more than 6 feet high and it has two immersion heaters, one at the bottom and the second about half way up. They are both connected to traditional looking switches and they work! The other bit of the house has an old fashioned header tank with a hot water cylinder. It also has an immersion so I would be surprised if Clariman's Megaflo does not have at least one immersion heater.


Dod

[Mike4]

Firstly, the way to tell if your water is being heated by gas or electricity is to look at your electricity bills. If they are nose-bleedingly high, its done by gas. If they are so high you worry you're gonna need a mortgage to pay them, it's prolly on the leccy.

Secondly, although having not seen it, the chances are high the two cables are connected to 1) the control thermostat which asks the boiler to light when the tank cools a little, and 2) the immersion heater element.

When there is no obvious switch for the immersion, it will probably be somewhere 'convenient' like on the landing wall or downstairs in the kitchen. Can you think of a random switch anywhere in the house that doesn't appear to have a purpose? That will be it!

Turn it on and look at your leccy meter to see if it starts spinning like the blades on my helicopter....

[redsturgeon]

One thing you're probably aware of but I'll mention it as people often aren't....

Your hot water cylinder probably has an electric immersion heater for emergency hot water in the event of gas boiler failure. Turn it ON if you have one!

We have a megaflo tank. Would the immersion be on that? Hopefully we'll have enough hot water in the tank for showers this morning anyway, but a backup would be good.

On the heating front I'm really glad we have an effective gas fire in the living room and a couple of free standing electric radiators as backup.

Most MegaFLO models come with immersion heater element factory-fitted. The installer needs to fit a big fat cable connecting it to a wall isolator switch but many don't bother. So if you don't have a second, fat cable going directly to a wall switch, your immersion heater hasn't been wired up.

Quickest fix for this (assuming no wall switch exists for an immersion heater) is to get a metre or two of heat resistant 1.5mm or fatter (technical term) cable and connect one end to the heater element terminals and the other to a 3-pin plug, then plug it in using a 13A extension cable.

Yes I did this when we were changing boilers. Exactly as you said immersion fitted but never connected. Fitted a 13 amp plug to the wires and stuck it in an extension lead. Worked for the few days I needed it.

John

[Dod101]

Firstly, the way to tell if your water is being heated by gas or electricity is to look at your electricity bills. If they are nose-bleedingly high, its done by gas. If they are so high you worry you're gonna need a mortgage to pay them, it's prolly on the leccy.

Secondly, although having not seen it, the chances are high the two cables are connected to 1) the control thermostat which asks the boiler to light when the tank cools a little, and 2) the immersion heater element.

When there is no obvious switch for the immersion, it will probably be somewhere 'convenient' like on the landing wall or downstairs in the kitchen. Can you think of a random switch anywhere in the house that doesn't appear to have a purpose? That will be it!

Turn it on and look at your leccy meter to see if it starts spinning like the blades on my helicopter....

This man knows what he is talking about. In my traditional hot water cylinder, I have a switch coming from the immersion heater but switching it on does not make the immersion work. For some very strange reason, there is another switch in my utility room which controls the switch which controls the immersion heater. I spent a long while some years back trying to work out why that immersion heater was not working! No idea why it is wired like that but much of my electrics I do not understand.
Dod

[Mike4]

Firstly, the way to tell if your water is being heated by gas or electricity is to look at your electricity bills. If they are nose-bleedingly high, its done by gas. If they are so high you worry you're gonna need a mortgage to pay them, it's prolly on the leccy.

Secondly, although having not seen it, the chances are high the two cables are connected to 1) the control thermostat which asks the boiler to light when the tank cools a little, and 2) the immersion heater element.

When there is no obvious switch for the immersion, it will probably be somewhere 'convenient' like on the landing wall or downstairs in the kitchen. Can you think of a random switch anywhere in the house that doesn't appear to have a purpose? That will be it!

Turn it on and look at your leccy meter to see if it starts spinning like the blades on my helicopter....

This man knows what he is talking about. In my traditional hot water cylinder, I have a switch coming from the immersion heater but switching it on does not make the immersion work. For some very strange reason, there is another switch in my utility room which controls the switch which controls the immersion heater. I spent a long while some years back trying to work out why that immersion heater was not working! No idea why it is wired like that but much of my electrics I do not understand.
Dod

I very much doubt the installer knows why, either!!

Never underestimate the stupidity of a sub-section of tradesmen. There is a truly massive spectrum of abilities in the trades.

[Clariman]

Well we've had 2 engineers out today: the first was a young lad who was very helpful but not very experienced. His backup came half an hour ago and says the boiler is fine but PCB is knackered. Unfortunately the company doesn't carry high value parts as standard because they are worried their guys will do homers. So it will be ordered first thing Monday.

He was also adamant that our megaflo is setup so that it heats our water rather than the boiler and that is what the Hive water heating controls. That's good news because it means we have hot water. I hope he is right because if I have a bath and there is nothing left for Mrs C she'll kill me.