Vaillant 438 boiler - hot water only not working

[mervmatt]

I have a Vaillant 438 boiler, newly installed, and cannot seem to get the hot water to come on independently of the heating. I am using a Vaillant 140 programmer onboard the boiler, a Sunvic TLX7501 room thermostat, 2 x Honeywell diverter valve and an Ariston unvented indirect water cylinder for the hot water with a high limit stat in line with the cylinder thermostat.

This is an 'S' plan system and I think I may have wrongly wired the hot water thermostat and high limit stat, which could be causing the problem.

The heating will work independently but the hot water will only work when the heating is also on.

Can anyone help with suggestions re solving this problem? Many thanks.

 

[mickyg]

how is that wired then with the 140?? thats not gonna work is it. bin the timer and wire up a normal programmer.
Why don't you get the installer back.

 

[mr-crs]

Are you using the vr 65 control centre with this boiler set up ? it wont work properly without it. I know the default setting is for priority hot water and you can change this using the menu described in the back of the manual for the vr 65 I have not seen hot water only when heating is on hope this helps.

 

[mervmatt]

how is that wired then with the 140?? thats not gonna work is it. bin the timer and wire up a normal programmer.
Why don't you get the installer back.

Although I don't fully understand the boiler workings, the installer instructions for the Ecotec plus seems to indicate that I can use terminal 4 of the control panel to run 230v controls such as zone valves, programmers, room thermostats and cylnder thermostats, providing I remove the link between 3 and 4. When I contacted Vaillant on Friday, they sent me wiring details for an Ecotec 400 boiler with hot water cylinder and heating zone 'S' plan and I have wired it in accordance with their instructions, the wiring of the limit stat that I am using to diverter valve does not seem to be complete.

Thanks for your help.

 

[mervmatt]

Are you using the vr 65 control centre with this boiler set up ? it wont work properly without it. I know the default setting is for priority hot water and you can change this using the menu described in the back of the manual for the vr 65 I have not seen hot water only when heating is on hope this helps.

Just to confirm, are you saying that this particular boiler will not operate on a hot water only setting without me purchasing the vr65 control centre? If I don't wish to go to this further expense, is the only way to get hot water by having the heating on as well? Thanks for your help.

 

[mickyg]

of course not, how do you think the controller tells the hw zone valve to open?

 

[mervmatt]

of course not, how do you think the controller tells the hw zone valve to open?

Not being the installer, don't really know. Would have been really helpful to have been instructed how to get the hot water only working. However, Not to worry, will ring Vaillant again on Monday.

 

[mickyg]

I gave you the answer earlier on, but you choose to ignore that. Vaillant are not going to correct your mistakes.
Firstly you didn't say who installed it. Its they who should be sorting out this mess, especially as you raised concerns your unveneted cylinder could be wired wrong, in which case you could be creating a dangerous situation.

bin the timer and wire up a normal programmer

 

[mervmatt]

I gave you the answer earlier on, but you choose to ignore that. Vaillant are not going to correct your mistakes.
Firstly you didn't say who installed it. Its they who should be sorting out this mess, especially as you raised concerns your unveneted cylinder could be wired wrong, in which case you could be creating a dangerous situation.

bin the timer and wire up a normal programmer

It was installed by a Corgi reg. installer and wired up by an electrician. I did take on board what you said about ditching the 140 but Vaillant know the controls I am using and did not say that the 140 would not work with the system I have got. Obviously, I need to double check this with them especially as the 140 was recommended by the supplier. Reading the documentation, it seems to indicate that I need to buy an accessory in order to work the hot water independently. Vaillant have been helpful and sent me two lots of wiring diagrams but the hot water still will not come on independently. Being the weekend, I was just trying to see if anybody else knew the answer. Thanks for trying to help anyway.

 

[mickyg]

well the installers should be called to sort this mess out. but basically you'd be better off without the 140. It has no advantage over a normal programmer, and you would need the VR65 to make it work.
Can't believe they installed it like this, then again, most electricians are clueless with heating wiring.

 

[mr-crs]

mikeyg is correct that boiler using that built in timer is designed to work using the vr 65, you need to get your installer back dont bother ringing Vaillant you will be on hold for ages to be told the same thing.

 

[mervmatt]

well the installers should be called to sort this mess out. but basically you'd be better off without the 140. It has no advantage over a normal programmer, and you would need the VR65 to make it work.
Can't believe they installed it like this, then again, most electricians are clueless with heating wiring.

o.k. thanks v. much for that. The installer did initially supply a mechanical programmer (one with the pins) but my wife said she wanted a digital programmer and this is what he and the suppliers came up with. Nobody's fault really I think. As you said, the electrician was a domestic installer - I didn't realise you needed one who specialised in boiler wiring. None of us knew that we needed the accessory but my wife noticed this in the documentation and then the other man on this site who has replied to us also said this was what we needed. We just got confused because Vaillant said nothing about it on Friday when I spoke to them and told them everything I was using.

Anyway, thanks for the help. We'll change the programmer again.

 

[mervmatt]

mikeyg is correct that boiler using that built in timer is designed to work using the vr 65, you need to get your installer back dont bother ringing Vaillant you will be on hold for ages to be told the same thing.

Thanks. I'm Merv's wife. I did reply to you yesterday but think I might have sent the reply meant for you to mikeyg instead and managed to upset him a bit, I think. We just could not understand why Vaillant did not say anything about using the vr65 when we spoke to them and told them about the different controls we were using.

Back to the drawing board regarding the programmer - really do need to get hot water working independently of heating. Thanks for all the help.

 

[gas4you]

You must get a VR65 installed. The 140 needs to talk to this via ebus and not 240VAC.

The zone valves, room stat and cyl stat are then all connected to the VR65, not a normal wiring center. The VR65 has its own 240VAC supply and fused isolator switch.

Vaillant tech help are useless, only good for giving you a large phone bill.

 

[GeorgeBramwell]

You must get a VR65 installed. The 140 needs to talk to this via ebus and not 240VAC.

Nice van you have.

http://drlgas.co.uk/