Replace Sunvic TLX with Honeywell CM927 help please.

[gerardo]

Following on from a previous post, I have purchased the CM927 and would like some advice please.

For info, Remeha Avanta system boiler, timer below, Sunvic Thermostat in the hall. Previously had a Salus RT500RF but two receivers failed so now going to try the Honeywell. The Sunvic has been put into use until the weekend.

The Sunvic has an earth, then these terminals with this info from the spec sheet:

3 (live)
1 (I assume switched live!)
4 (neutral)

There are, however, two wires in the neutral terminal

Would it be possible for someone to confirm that the new connection will be in the Honeywell:

Wire from Sunvic terminal 3 (live) to the first L (middle terminal) on the Honeywell.

Wire from Sunvic terminal 1 to terminal B on the Honeywell.

Both neutral wires from Sunvic terminal 4 to terminal N on the Honeywell.

Does the Honeywell need jumper wires across the two L terminals or is this done by the electronics in the receiver? The Salus had a link wire.

The timer will be left in "on" mode to keep the Honeywell powered.

Thanks in advance.

 

[gerardo]

One more question, do I need to link L to A or is this done within the honeywell?

 

[D_Hailsham]

Which Sunvic thermostat do you have?

 

[gerardo]

Sorry, will have to look tomorrow. It is 230v mechanical. I have tested the Honeywell using a mains lead and light fitting and eventually got it working. I wired the mains to the left L and N, linked the second L to A, connected the bulb to B and back to the N on the left.

The unit needed to be bonded. I have documented what eventually worked but initially the relay would not power the bulb. This may have been my wiring!

Does this sound OK?

 

[D_Hailsham]

Sorry, will have to look tomorrow. It is 230v mechanical. I have tested the Honeywell using a mains lead and light fitting and eventually got it working. I wired the mains to the left L and N, linked the second L to A, connected the bulb to B and back to the N on the left.

You seem to have sussed it out yourself. The bulb represents the boiler, which should have its own neutral connection. So B just connects to boiler switched live. However I would still connect the two neutrals from the Sunvic to the Honeywell N terminal as one of them may be providing a neutral elsewhere.

The unit needed to be bonded.

Do you mean the Honeywell Relay box? That definitely should not be necessary: (a) the box is double insulated; (b) there is no earth terminal.

 

[gerardo]

Thanks, yes I meant the units did not commumicate and needed to be joined via wireless!

I intend to do this in the light hours of the weekend. The terminals do not look like they will hold two wires; that may be tricky for my big hands!

 

[D_Hailsham]

Thanks, yes I meant the units did not communicate and needed to be joined via wireless!

Got you. You were referring to binding the receiver and the control unit. I thought you were referring to earth bonding.

I intend to do this in the light hours of the weekend. The terminals do not look like they will hold two wires; that may be tricky for my big hands!

If you can trace where the two neutral wires go, you may be able to get rid of one or connect it somewhere else. Failing that, connect the two to a terminal block with a single wire into the relay box.

 

[gerardo]

Thanks again.

Unfortunately the boiler has once more failed to ignite when the thermostat is switched.

The problem when the Salus was fitted was that intermittently, the receiver would click and the LED became green, indicating power but the boiler would not start.

Thinking the relay had gone, I replaced with the simple Sunvic. As mentioned this has now failed to fire the boiler but has on repeated on/off of the thermostat. Not sure if that is relevant or whether the boiler is somehow "crashing".

Think it is time to call someone in; the boiler was fitted in Feb so may give the installer a call. Looks like the Honeywell may be fitted at a later date to avoid further confusion.

Any clues as to what to do next?

 

[D_Hailsham]

I replaced with the simple Sunvic. As mentioned this has now failed to fire the boiler but has on repeated on/off of the thermostat. Not sure if that is relevant or whether the boiler is somehow "crashing".

Presumably the installer left the Installation Manual with you. The Remeha stores up to 16 error codes, so it might be worth checking what they are as there could be a clue there. See page 55 to access the error codes. The meaning of the codes is on pages 52 and 53.

the boiler was fitted in Feb so may give the installer a call. Any clues as to what to do next?

Call the installer; the installation is still covered by his guarantee.

 

[gerardo]

Thanks for response.

Checked codes and:

ER1 E10 5t10 n1 t1 30 t2 34
and
CL er O 1

I think it is time to bail out on this and speak to the installer (message left) or with another installer a friend knows.

I am bemused as to why it is occassionally and the when turning the cylinder stat the boiler fires.

Does the thermostat control the zone valve and then the valve feeds back to the boiler?

Thanks for your time.

 

[D_Hailsham]

Checked codes and:

E10

Error 10 is explained on page as "No through flow during venting cycle" with some possible reasons. The first is Insufficient Water and suggests you check the pressure.

What does the pressure gauge read when the system is cold?

The other reasons need to be checked out by the installer.

I am bemused as to why it is occasionally and the when turning the cylinder stat the boiler fires.

Does the thermostat control the zone valve and then the valve feeds back to the boiler?

How many motorized valves do you have:- one, as in left pic; or two, as in right pic?

View media item 5946 View media item 11762

 

[gerardo]

It is the first one, next to the cylinder in the airing cupboard. The thing that confuses me is why it intermittently (not sure how often) the boiler fails for CH but not HW.

Does the valve return a feed to the boiler?

Thanks for bearing with me.

 

[D_Hailsham]

It is the first one, next to the cylinder in the airing cupboard. The thing that confuses me is why it intermittently (not sure how often) the boiler fails for CH but not HW.

Does the valve return a feed to the boiler?

To make it simple, when the hot water is being heated, alone or with CH on, the boiler is turned on and off by the cylinder thermostat. But when CH only is being heated the boiler is turned on and off by the room thermostat via the motorized valve. You can read a full explanation in How a mid-position valve works

From what you say, either the valve is not opening properly or the switches in the valve are faulty. The link above has fault finding instructions.

 

[gerardo]

Thanks for the help, so hopefully, the Honeywell will be on the wall this weekend and I will call upon an engineer to change the valve at some point. Seem to have had at least two of these go over tha last 10 years.

 

[D_Hailsham]

I will call upon an engineer to change the valve at some point.

Have you read the link in my last post? It explains how to fault find the valve. You may be able to repair it yourself.