Ideal ISAR HE 24 Fault.

[joel89]

hi all i am new to the forum, Im an industrial sparky by trade working in steel works. My sister rents out an apartment the tenant has wrecked it along with the boiler I had the same boiler in my house and had nothing but trouble with so I learnt quiet a bit on them, but of course she doesn't want to pay for a new boiler, the original fault I had was a dead short on the PCB boiling the main fuse in the spur so I have recently changed this the boiler fires perfectly on central heating and hot water, another fault I came across whilst testing was the room stat switch live was remaining energised so I've also changed this, the problem I have is that when the stat breaks the live it goes out and drops the switch live out to the PCB which takes out the burner light but the (C) is still shown on the front of boiler as though its calling for heat, and the boiler fan and pump still run. Could I have any advice on where to go from here?
Please can I not have call an engineer I haven't touched anything on the gas side, I work on gas fired furnaces at work So I have a good understanding of boilers and burners.

 

[ShaunCorbs]

Have you tested your not getting voltage at the boiler (s/l)

 

[joel89]

yes 230v in when stat on and 230v off when stat off, although when stat off I am getting 94v dc back down the switch live, as though its getting a back feed off the pcb DC Supply side

The pcb I bought was from a company that refurbs all Ideal pcbs, could it be anything daft like jumpers in wrong position?

 

[ShaunCorbs]

Well if your getting 240 back at the s/l when the stat is off

Disconnect your s/l wire from the stat and measure at the terminal if you still getting 240 board fault

I never buy recon boards unless there dis eg not being made and then there hit and miss

 

[joel89]

but also when I have turned off the stat to kill the central heating if I then run the hot water for a few seconds it then shuts off the boiler burner and Takes it back to (0) on the display to show no call for hot water or central heating

 

[ShaunCorbs]

but also when I have turned off the stat to kill the central heating if I then run the hot water for a few seconds it then shuts off the boiler burner and Takes it back to (0) on the display to show no call for hot water or central heating

Have you tried letting it do its thing for like 10 minutes after you turn the stat off ?

 

[joel89]

no mate I haven't could I be looking for a fault that isn't there?

 

[ShaunCorbs]

no mate I haven't could I be looking for a fault that isn't there?

Maybe, it could be as simple as pump overrun and the fan getting rid of the dregs of flue gasses left

 

[joel89]

I'll be going tomorrow I'll give it a go first so around 10 minutes would be fine on shutdowns?

 

[ShaunCorbs]

Yea but I would allow 15 just to be 100%

 

[Last Plumber]

Is everything plugged in correctly?
Internally

 

[SavageW]

Could be when your turning the stat down an then running the tap that it’s then using its preheat an the burner won’t fire until this has been used? When you turn the stat off an then open the hot tap are you getting hot water even though there is no demand at boiler display?

 

[joel89]

The hot water isn’t an issue that’s working correctly. As I shut off the central heating on the thermostat and leave it, The burner light goes out but (C) still remains on and I can hear the fan running for a considerable amount of time, but whilst the boiler is doing this if I then run the hot water tap burner kicks in runs the hot water and then I turn off the tap, the boiler within seconds goes to the (0) setting with no call for heat or hot water and no sound of the pump or fan

 

[Last Plumber]

What Happens when you turn it off on the programmer?

I asked about the plugs (by the way) because on this Boiler there is actually a pair the same and it is easy to get them crossed due to where they are.

Nothing blows or gets damaged if that happens, (not on the one I found anyway).

It's a long time since I came across that one and I can't remember what the Boiler behaved like now to be honest, just thought I'd ask as you've changed the board

 

[joel89]

The two you can across is the feed to the Screen display and the permenant live. Neutral. Switch live plug I plugged it in at the side of fuse carrier, Ill check that tonight could be why I am getting 95v DC back down the switch live! I know without checking the Display will be DC not AC.

 

[SavageW]

Just sounds like normal over-run from when you turn the heating off,after while should go back to 0 display with no demands

 

[joel89]

Been up tonight ran it shuts down after 6 minutes tried it 4 - 5 times and it works perfectly thanks for the advice!

 

[ShaunCorbs]

Thnx for getting back to us