Any heating gurus out there?

[mikel]

Been called to a heating problem, the system is a 'y' plan installed a few years ago by british gas, the customer had a new boiler installed recently a few weeks after the heating system started to 'play up'. The heating wouldn't come on at certain times. this is a brief diary from the customer over the past few days

24/12

Left water on timer heating came on with timer. Heating stayed on okay when hot water went off. As expected :0)

25/12

Hot water on with timer heating also came on but went off when hot water went off even though heating light on panel still on. Heating wouldn't come back on manual until hot water also put on manual but both went off. Couldn't get either back on manual during the day. Not good :0(

26/12

Hot water on with timer. Heating came on but again went off with hot water. :0(

27/12

Hot water on with timer heating stayed on when water wen off :0)

28/12

All okay on timer but not tried manual.

29/12

All okay on timer but not tried manual.

30/12

All okay on timer but not tried manual.

31/12

Heating left off on timer hot water came on weirdly so did some radiators. All off with timer and couldn't get heating on with manual even though light on panel was on until hot water on manual :0(

My first thoughts are that the programmer is not working correctly especially as the heating/hot water seem to work ok some of the time.

Anyone got any ideas

 

[Andy™]

3 port valve jamming/not switching?

 

[revjames]

I concur with Andy 3 port valve, take actuator off and try it manually then see if the programmer is opening and closing it as it should.

 

[Lurch]

3 port valve is the usual suspect. I'd check the cylinder stat as well.

I'd also take the 'worked fine before' with a pinch of salt, I'd first of all check and double check everything and make sure it is all wired up correctly before starting to look at anything else.

 

[PC Electrics]

I would check the 3 port valve first, programmer second.

Go to the honeywell site and download the electrical checkout lists.

 

[PC Electrics]

The Honeywell site is down at the moment. The checkout document is too big to make an attachment here, so email me (take the space out of the usename)@aol.com and I'll send you a copy

 

[professional]

Unless the programmer has been changed along with the boiler, I`d suspect the stepping motor in the 3 port mid-position valve. If it`s a decent make you may be able to just change the motor and leave the plumbing alone.

The commonest fault that I`ve come across on the cylinder stat is that of calling for hot water but not changing over when up to temp- resulting in no heating without hot water.

 

[mikel]

Had a look at the 'job' on saturday. Sod's law came into effect and the system appeared to be working ok. All wiring checked and tested in accordance with the Honeywell guide (thanks pcelectric). The only clue to any fault was when hot water only was selected the valve didn't shut off the heating, it stayed mid position. After speaking to client he elected to leave it as it is.

 

[PC Electrics]

Had a look at the 'job' on saturday. Sod's law came into effect and the system appeared to be working ok. All wiring checked and tested in accordance with the Honeywell guide (thanks pcelectric). The only clue to any fault was when hot water only was selected the valve didn't shut off the heating, it stayed mid position. After speaking to client he elected to leave it as it is.

Faulty mid position valve then. Could be the motor unit on the valve or the valve itself. If it's a Honeywell valve then the motor unit can be replaced on its own. If it is Honeywell you could remove the motor unit and see if it works okay unattached to the valve and also move the valve by hand to see if it's jammed.

Obviously if it is the valve or it's not a Honeywell then a system drain is required to replace the whole unit - best refer that job to a plumber. If he doesn't have it fixed it'll only annoy him or leave him without heating or hot water when he needs it most and he'll probably waste as much in gas over the next few years as it would cost to fix now.

Also if it is the valve then he would be wise to have the system properly refilled with clean water and inhibitor. It is possible that he has a dirty system and this has done the valve in (get a plumber to check this). If this should be so, then it's doubly important to get it sorted 'cos a dirty sytem will do for his boiler in fairly short order too.

 

[mikel]

Cheers for that. He's just had a new boiler fitted, well within the last 6 months. The valve is a sunvic one do't know much about them tho,

 

[Andy™]

its not just honeywell who have replacement heads, many other makes also have them. but it may be hard finding it if its another make. try taking the head apart - may just be a dodgy contact on the switches

 

[sparkyrj]

It could be just a matter of the hot water satisfied connection on the cylinder stat not operating for some reason and not closing the valve.

 

[batty]

I would wonder if boiler is wired correctly. I got called to a job were boiler was doing allsorts of strange things. To cut a long story short it had never been wired correctly and only had live neutral and earth and no switched live. Luckily with a bit of fiddling with wiring I could get it sorted. Now British Gas new about it being not wired correctly but did not want to sort it out. Makes you think though.

Batty

 

[mikel]

his is a brand new boiler, wiring diagrams for it show only a live, neutral and earth. So its wired as per the wiring instructions in the information and as per honeywell y plan so the live is actually a switched live from the 10 way junction box.

 

[batty]

his is a brand new boiler, wiring diagrams for it show only a live, neutral and earth. So its wired as per the wiring instructions in the information and as per honeywell y plan so the live is actually a switched live from the 10 way junction box.

So needs no permanant live? Most do these days for pump over run.

 

[Theorysparky]

I would wonder if boiler is wired correctly. I got called to a job were boiler was doing allsorts of strange things. To cut a long story short it had never been wired correctly and only had live neutral and earth and no switched live. Luckily with a bit of fiddling with wiring I could get it sorted. Now British Gas new about it being not wired correctly but did not want to sort it out. Makes you think though.Batty

Funny that......

i had exactly the same fault last year....3 years it was like that...

manufacturer out changing boards etc...didnt want to touch the wiring mess in the airing cupboard......

the customer successfully got my invoice paid by the heating company who put the boiler in..........

 

[batty]

Funny that......i had exactly the same fault last year....3 years it was like that...

manufacturer out changing boards etc...didnt want to touch the wiring mess in the airing cupboard......

the customer successfully got my invoice paid by the heating company who put the boiler in..........

Nice they paid it.

 

[PC Electrics]

I'm with Batty - something smells wrong about a brand new boiler that only requires a switched live. No pump over-run or condensate pump?

Make & model of boiler?

The suggestion about the tank stat would be a good one if it weren't that he's checked that out already using the Honeywell fault finding charts.

 

[tamdee]

Hi pc, we sometimes fit boilers that dont require a pump overun(although the majority of the boilers do.) High water content boilers they say can disperse the heat easily although the low water content ones require the overun to disperse the heat from the boiler. Probably about 90% of boilers condensate to waste just by downward running.if a pump has to be used (if route to waste rises)then we usually fit an external one.

It can be a real pest when we sell a boiler that requires a permanent feed and pump overun and the original has only a switch wire.especially when a lot of the controls are fitted in an upstairs cupboard

 

[batty]

Hi pc, we sometimes fit boilers that dont require a pump overun(although the majority of the boilers do.) High water content boilers they say can disperse the heat easily although the low water content ones require the overun to disperse the heat from the boiler. Probably about 90% of boilers condensate to waste just by downward running.if a pump has to be used (if route to waste rises)then we usually fit an external one.It can be a real pest when we sell a boiler that requires a permanent feed and pump overun and the original has only a switch wire.especially when a lot of the controls are fitted in an upstairs cupboard

Isn't that what the cpc is for.

:coat