Good old Powermax 155x hot water problem

[mcyoungy]

Powermax 155x sealed system, approx 8 years old.

The fault is that in general I can only get hot water when the central heating is on. Although sometimes can briefly get it if just water turned on and boiler cold, but once it gets to temp doesn't ignite again, it tries 3 or 4 times to fire then locks out.

If I turn on a hot tap and run the heating then the hot water supply is fine.

I have fitted a new blender valve without making any difference!

Could it be that the external heat exchanger is fouled on the primary side? The flow from the hot taps is as good as it's ever been in the last 4 years.

This fault started after having part drained the system to address a deflated expansion vessel.

Or should look at the pump first?

 

[Beerlover]

Sounds like the flowswitch may be duff, The dhw pump will kick in when the store is recharging - this may be all that is giving you hot water.

 

[mcyoungy]

Thanks but I don't think it is. The pump runs because the flow switch makes. The burner tries to ignite and trips 3 or 4 times then locks out.

 

[Beerlover]

Sorry didn't read the post in full.

What issue is the pektron unit - when I left they were on D (the last letter on the back of the sealed box). Earlier versions could cause random lockouts when hot.

Baxipotti, will know more.

Good luck, I only tried to help.

"Tried and failed; no! tried and died" - Dune

 

[mcyoungy]

blimey.............................. what's a pektron unit?

 

[mysteryman]

He probably means a Pactrol box. This is the control box for the gas valve, fan, ignition etc.

Sounds to me as if your boiler needs servicing. Fiddling with blending valves won't cure lockout problems!

 

[mcyoungy]

So what will? The heating works fine......