CH/HW Not working as expected

[pmurfitt]

Hi All,

I'm currently living in a rented house over 3 floors. In the kitchen on the ground floor, we have a Worcester Greenstar 15Ri (think that's the right model) with a single main power switch under it which seems to control the entire system. On the second floor, we have the lounge and main bathroom - along with a Honeywell T6360 room thermostat. On the top floor, there's two bedrooms and outside of both of them is the main heating control panel.

When we moved in, the heating control panel was an old style CH/HW mechanical timed device - which had stopped working (the timer that is, everything else was ok with it). We got the property management to get a plumber to replace this as we didn't want to have to run the heating on 24/7 as we were with the water!

Unfortunately, since then we've had totally odd behaviour with the system. The control panel was changed over with a Honeywell ST9500C which is a 2 zone panel. In the attic we have the HW/CW tanks, a Grundig pump and a Honeywell HW stat and Honeywell 3-way valve along with a Honeywell junction box (with a gigantic mess of cables coming out of it :rolleyes2.

From what I can tell, this is a 'Y Plan' system. The main issue is that when the control panel has both 'zones' set to off, the boiler sometimes doesn't shut off (can see the green light on the Worcester is still on). I would fully expect that when the control panel to be off that the boiler would stop firing gas immediately (even if the pump were to stay on for a bit). I've done some testing on the system, and finally worked out which 'zone' is for the heating and which is for the water (as the plumber never told us) and currently have the hot water on a timed schedule.

I believe that the replacement control panel is completely wrong for our setup - would expect the ST9500C to be used with a system which has 2 1-way valves after the pump rather than a 3 way one. Is this correct? It's hard enough trying to get the plumber back, but if I can state that he's installed the wrong control panel (which should be obvious given the plumbing I've seen in the attic) we should find it easier to get him back to change it.

So the main question is, can the ST9500C be used in a 'Y Plan' CW/HW setup with a 3 way valve? When the plumber was over, it wasn't for long and he didn't go into the attic (so couldn't have touched the main wiring control panel) so would it be possible even make a 2-zone panel work with a single valve without changing any extra wiring?

Thanks for any help, if you need any more information I'd be happy to provide it.

 

[steadyon]

The ST9500C can be used with a three port valve in the "Y" plan configuration, although the wiring isn't shown in the Honeywell guide / leaflet that comes with the controller. I suspect your problem is one of:

1. The ST9500C has not been wired in correctly, which could be an issue over conversion from the old programmer.
2. The ST9500C is wired correctly, but there is a fault with the three port valve.

There are other, more esoteric, possible reasons, but I think you are going to need a good engineer to fully identify and rectify.

 

[pmurfitt]

Thanks for the information. As things were working fine (except the timer) before the control panel was changed, I think it would be likely that it just wasn't wired in correctly.

I found the Honeywell Wiring Guide Issue 16 (honeywelluk.com/documents/all/pdf/wiring%20guide%20issue%2016.pdf) which seems to be very good in showing 'connect this to this terminal' and also has the connection layout for the 9500. Do you think it's worth me tracing all of the wiring out to try to locate the issue?

 

[Simon F]

I'm currently living in a rented house

Thanks for the information. As things were working fine (except the timer) before the control panel was changed, I think it would be likely that it just wasn't wired in correctly. Do you think it's worth me tracing all of the wiring out to try to locate the issue?

get in touch with whoever takes the rent and get them to sort it for you.
should you be fixing it, possibly electrocuting yourself, making it worse etc ?? - NO

 

[jtsplumbing]

I agree with simon F , why are you messing around with this system its not your problem ! and you could make things worse, and finish up haveing to pay out to put it right !! LEAVE IT ALONE

 

[pmurfitt]

Decided not to mess with it in the end, agree that it makes more sense. Will have to get the plumber in, it'll just take ages for them to get their act together and for me to prove that he installed the new panel wrong (hence the questions about wiring it up and having to look at the junction box).

 

[jtsplumbing]

How can you prove its installed wrong ? are you in the trade ? Was he a GSR or just a plumber ? last thing you want to do is open up the wireing center, do you know how long the system has had a problem ? it could be one of the other controls that is at fault !

 

[pmurfitt]

Well it's installed wrong as it doesn't work as it should. I'm not a plumber but I have a lot of experience in domestic electrical installations. The fact the guy put in a 2-zone timer instead of one designed to work with a single 3-way valve without then changing the wiring to work in this configuration as steadyon already stated means he's done it wrong. There's no issue with any other part of the system as everything was working perfectly (with the exception of the timer) before this was changed. I've got all the information I need now to go back to him.

 

[jtsplumbing]

Ho another sparks , most of the ones ive come accross could not wire up a heating system if their life depended on it ! somthing with more than than 3 wires is a mistery. are you a qualifed sparks ? or a mate ?

 

[Nostrum]

You've got the stick by the other end .

regardless on 2 zone valves or 1 3 port you need a 2 channel programmer, otherwise how are you going to control the two separately?

no disrespect but heating controls require a slightly different logic to domestic wiring, hence why a lot of domestic electricians wire them up wrong (not all I may add, but some)

sounds like a wire out of place to me, but it would be wrong for me to go into any more detail and potentially encourage you (or anyone else who reads this ithe future) to work on something you are not familiar with.

it obviously doesn't work as it should so get the landlord to send an electrician who is familiar with heating controls around to sort it out.

 

[DirksPlumbing]

You've got the stick by the other end ...

Full ack.

Just to add: No, the heating system will not reflect your play on the button in real time. As the demand gets controlled via microswitches which get operated by the 2(3) port valve. And depending on the make and model (and wiring) it can take some time before the demand signal gets cut after you swiched it off. But indeed not hours. As others have stated, this is to much for a lot of electricians already. Let your Landlord deal with it.