The dreaded Flow Switch - Potterton Promax/Baxi Solo/Main Heat 

Brilliant video as always. Had one this evening and used the wet vac as the thing wouldn't stop dripping. Them clamps are a nightmare. The flow switch snapped off inside the boiler which wasn't fun, but all sort now. Video was a god send cheers!

Nice one , what a fantastic design of a boiler , only ever done one and had a problem re sealing the flow switch , got it after third attempt as it was rotten.....😡 cheers mate...👍

Cheers, Havnt done one of these yet, good to see what I'm in for 👍

Looks difficult great video and tips

Another quality fix 👏👏👍

Still got it done mate well done

Top work

What a Pig of a boiler!! Great video mate, been there got the cap & tee shirt!!

I did one today, was easy peasy, drain down, remove bracket, uncouple flow pipe, remove flow switch, lube up new one and repressurise the system, test for leaks, took no more than 30 mins including going to the merchant for parts. All you need to do is cover the PCB casing. Panic over problem solved.

I was looking to get a Baxi 800 heat only boiler installed but discovered that they own potterton and main. On the face of it these heat only models look the same. do you know if that's true for the internals or are there some differences? Or is the difference just the warranty lengths and getting a filter with a Baxi?

Help I have a question. I am putting in a new programmer I’ve lifted off the face of the old one and there are 2 red wires going into live, 2 blue going into negative and a loop going from the live to number 1 and a yellow going into 3. I’m a little confused can you advise please. Thanks

I have been watching your channel for a long time, I have baxi solo 2 pf the overheat lamp lights up and he does not want to turn on thanks for any help

I have an igiton issue on customers version. They said over phone, not igniting. Not worked on old boile like this before.

What was the fault the customer said to change the flow switch?

i have got one to replace its leaking at the bottom where it connects to the boiler. its in a cupbaord pipes go up and tight to the wall no compression fittings just a straight soldered coupler and the flue goes out to the side no room at all!! not sure i fancy this

Good work not to bad this one as you have access if was in a cupboard then it can be tricky

Nice explanation again CP. Somehow that does not look ideal. Lol. Would hate to think how difficult it would be if flue was to the right and flow and return pipework went upwards too. Would it mean complete drain down ?

had one of these today, kept firing and then extinguishing, locked out after five times. found the condensate completely blocked (but dry inside). the condensate was running down R/H side casing inside. probably the water was stopping half wave rectification? then when I washed the trap out, water on the trap's electrical connectors stopped it from firing. as soon as removed the wire to the trap, ran fine. dried the trap in situ with a hair drier and it worked.

Thanks for the great video. I’ve got the same boiler, Potterton 12SL Promax. I was wondering if you could please give me some advice, I’ve been having further problems since changing the flow switch. I’ve recently changed out the flow switch as well, It worked well for the first day but today it started locking out. After firing up & working for 5 minutes, The water coming into the boiler is noisy. it was cutting out & all three lights were out on the PCB housing & the reset switch wasn’t working. For me to fire it up, I had to turn of & turn on the fuse coving the boiler on the house main fuse panel. The boiler isn’t flicking the fuse. I need to turn it on & then of myself. I would appreciate any advice to resolve this problem. Thank you in advance. Richy

Hey.. Agreed ball ache job also they leak and drip onto pcb and cause it to blow, i take it is closed circuit in rest and then goes open when working? Thanks for the video bruv 👍🏻

Good job. Can you confirm how you diagnosed it was the flow switch that was at fault? What were the symptoms?

Hello mate. Did you change the flow switch because you had a solid light and two flashing green lights due to no or reverse circulation? Thanks

super.

I have the same issue and replaced the flow switch worked fine for 2 weeks but now gone again. I did notice there was sludge in the heat exchanger how would this be cleaned out?

i think if i was going to disconnect a compression joint and take out the pipe as well i would have put a compression cap end on the open ended pipe just in case the air lock failed . Good video though well done 😀

Hi My Potterton promax sl 15 looks exactly the same as this one but I don’t have an air pressure switch? Do you know why this is? Regards

Hello mate We got same boiler hot water working fine. But no heating although changed zone valve,thermostat and programmer. What could be the issue

GREAT VIDEO!! CAN ANYONE HOW YOU SEAL THE NEW ONE IN DOES IT COME WITH A SEAL OR DO YOU HAVE TO SEAL IT IN??

Hi mate where are you based?

I went to a job where the flow switch was replaced but the engineer that replaced it forgot the bracket! they used a cable tie and the clip to hold it together!

horrible boiler hate them with a passion i always take the pcb out when i change the flow switch

I hate those boilers they must be the worst out there , not one good thing about them

Great concept but the boilers themselves are rubbish. The seals around the case perish quicker than a mouldy banana. This causes the overheat to activate but there are two on this. Poorly made but so easy to fit and no need for a permanent mains live supply is the only reason to fit. If you have 4 wires go better than these

Bad design.