New Baxi boiler - constantly heating water even when off?

[smithn]

Hi all,

I have today had a new Baxi Solo HE 15 installed.

I have a fully pumped system. New Diverter valve, Grundfoss pump 2 years old ish, so quite new & working fine (currently on lowest of 3 speeds). Potterton programmer EP2000/2 (16 programme). Recently installed.

Old boiler worked fine in terms of switching HW/CH and staying off if both CH & HW set to OFF - only replaced due to badly corroded heat exchanger (on advice of plumber who serviced boiler).

Anyway, it seems that even if the controller has both CH & HW OFF, boiler kicks in for a few seconds every couple of minutes and heats the water - HW is very hot! I practically emptied the tank of hot water (just by turning hot water taps on and replacing with cold in the tank) but the boiler kicked in and continued to heat the hot water.

I don't understand! I will be calling engineer back - but any heads up in advance would help me to getting the right fix. Any suggestions?

Thanks all!

 

[twgas]

I'd be checking the wiring first, if a new valve has been fitted a wire or two may be wronglyconnected.

I practically emptied the tank of hot water (just by turning hot water taps on and replacing with cold in the tank) but the boiler kicked in and continued to heat the hot water.

dont really understand this statement

 

[smithn]

Thanks for the quick reply.

The valve was replaced a couple of months ago and was working fine with the old boiler (I had to wire it as the 'plumber' couldn't get it working back then!).

So in terms of wiring the only change I am aware of is wiring in the new boiler - no wiring of anything else.

In terms of 'emptying the tank of hot water' - what I wanted to do was turn the tank cold hence turn the hot taps on - didn't actually 'empty' the tank of water, but just let the tank refill itself with cold to see what effect it had on the boiler. Quite simply the boiler kicked in and heated the water again even though the selector for the hot water was off!

Could the wiring at the boiler actually affect whether the boiler over-rides the programmer?

BTW - the cylinder thermostat no longer 'clicks' when you twist it to set the temp (it used to and would switch system off). The plumber did manage to trip my electrics and the other through is that he damaged the programmer....

Any further thoughts?

Thanks

 

[smithn]

Anyone any thoughts? Wiring seems the most likely...

 

[Gas2Air]

You had to wire it?

 

[smithn]

Urm, yep! Had a new 3 way valve put on, but because it was old switchmaster replacement it needed 'shorting' two wires - or at least wiring 2 together which were previously seperate due to old switchmaster valve having 6 wires and new valve only 5. Took plumber nearly all day and left it not quite working proper. Took me 30 mins & system working fine. I'll say no more Sometimes a little step back and reading of the installation/wiring diagrams is all it needs!!

Anyways, have assumed that on new boiler today no adjustments to teh wiring at the programmer was made - assumed only the wiring at the boiler, so am confused as to why HW would be constantly on even though programmer is switched off. Any ideas?

 

[Gas2Air]

Ok. The switchmaster had a yellow? Confused on the "shorting"?

 

[smithn]

Yes, but looped the red to orange iirc - was a little while ago... is this leading somewhere?

 

[smithn]

If it helps, Switchmaster had:

Blue
Yellow
Orange
White
Red
Earth

Rewired as:
Blue
White
Orange + red
Grey
--
Earth

IIRC

Does this offer anything further - much appreciate your help

 

[nicknox]

Did your last boiler have a permanent live supply (for pump overrun)? Your new one dosen't need one so may have been wired incorrectly.

 

[Agile]

A plumber does plumbing!

A heating engineer should be totally competent to wire up any system and fault find as well.

I dont think your "plumber" was up to the job! I do hope he was CORGi registered and is going to notify CORGI of your new boiler??

Tony

 

[smithn]

Thanks guys.

A slight update. I woke up in the middle of the night to all the heating on - even though the programmer was off! So had to completely switch the system off. So it seems that the boiler is heating whatever circuit the last position the mid-valve was at.

Turned system back on this morning - programmer is still set to off - and boiler has kicked in.

I do believe that the previous boiler (an Apollo) used an overun function.

Given the update above this could still be the overrun incorrectly wired?

I have looked at the wiring diagram in the installation guide and it does refer to wiring an optional overrun in?

Its also gurgling an awful lot which suggests to me that there is a reasonable amount of air still trapped...

Re: plumber - its an 'engineering' company and is corgi registered - don't know about notifying corgi of the installation - I've not had an official certificate from them although they completed the installation page in the boiler handbook...

I intend to follow up with Corgi...

 

[baxpoti]

just tio eliminate..........
Take the case off of the boiler, is there anything connected to the terminal marked P/F?
With timers and stats off, is the live to the boiler still live?

 

[smithn]

Hi,

Yes - connected to the 'optional pump feed' terminal is a blue wire tagged with red electrical tape...

Noting something about TRV'd systems not needing a room thermostat - I have one but it doesn't switch the system off once satisfied as far as I can tell...

Also tank thermostat doesn't seem to work anymore...

Sorry, don't know how to check if still live other than when all switches are off boiler still kicks in...

 

[baxpoti]

Yes - connected to the 'optional pump feed' terminal is a blue wire tagged with red electrical tape...

Unless you have TRVs on ALL rads and no roomstat this is incorrect. (should be coloured brown)

Sorry, don't know how to check if still live other than when all switches are off boiler still kicks in...

Green light on boiler stays on?