No connection on boiler to receive wiring centre - what to do?

[sb1202]

Need a workaround for this situation. Having retrofit UFH installed. Plumber installed the s-plan pipework for 2 zone (UFH + CH). Everything went to plan until we tried to connect the wiring centre to the boiler and hit a big snag.  There is no connection on the boiler for the COM/NO from the wiring centre. It's a Navien LCB700 oil and when we spoke to their tech support, they confirmed there is no connection.  

 

Setup is:  

ZONE 1 (CH/DHW) = Drayton 2 port zone valve to be wired to boiler via Honeywell wiring centre/terminal.  

ZONE2 (UFH) = Drayton 2 port zone valve, 5 port manifold + 5 actuators, 5 wired room stats. Waterline wiring centre (diagram attached). 

 

Everything hooks up to the UFH wiring centre correctly, but we can't connect the wiring centre to the boiler and we're both stumped.

Would this work for the UFH zone?  Connect a timer to the wiring centre, and use the COM/NO connection on the timer instead. (Thinking of a Danfoss TS710). This way, leaving the timer on full time, the room stats will control the UFH.  

The timer would connect to the boiler via the CONM4 terminal live/switched live. (See Navien diagram)



 

 

 

 

[ProDave]

Can you post a higher resolution copy of the pictures. Even if I zoom in they are too blurred to read.

 

Or more simply, a boiler won't have a "com / no" connection, it will normally expect a switched L to fire it so connect L to Com and then the NO will be a switched L to fire the boiler.

 

This is what happens often when a plumber connects something a little out of the ordinary, he does not understand it and cannot work it out.  (no offence to certain plumbers on here who are well capable of integrating different kit)

[sb1202]

14 minutes ago, ProDave said:

Or more simply, a boiler won't have a "com / no" connection, it will normally expect a switched L to fire it so connect L to Com and then the NO will be a switched L to fire the boiler.

The COM/NO connection here is a volt free/relay connection. It sends a signal from the wiring centre to the boiler to call for heat. Most boilers will have a 230v terminal side and a low/no volt terminal side on the main circuit board for connecting external controllers. This particular boiler doesn't and Navien confirmed it doesn't.  The plumber knows his stuff and has never came across this scenario before.

 

[ProDave]

So what DOES the boiler have instead?  I have never seen a boiler that does not have some form of call for heat.

 

That is that terminal block in your diagram above?  Is that the boiler?  Wiring centre?  UFH controller?

 

What ate the terminals F and L?

 

Perhaps post a link to the instructions for your particular boiler?

 

None of the information so far is making sense (to me)

[JohnMo]

Install manual has about 10 pages of connection options, including the dip switches options.

 

Trouble is the boiler is quite smart, looks to do PDHW out the box and WC, but normal UK install does S plan, why?

[sb1202]

26 minutes ago, JohnMo said:

Trouble is the boiler is quite smart

Yeah, and that's the problem. It uses their own "smart plus" technology which us LORA RF based. All calls are made from RF smart stats to a RF comms module that is wired to the boiler. Presumably, with all the calls to the module, they decided there was no need for a volt free terminal on the main circuit board.  It does s-plan, multi zone etc as standard, but it relies on adding their smart RF wiring centre, and again, this communicates with the RF module.  

[JohnMo]

13 minutes ago, sb1202 said:

volt free terminal

Lots of boilers don't use volt free. So nothing unusual there.

 

14 minutes ago, sb1202 said:

relies on adding their smart RF wiring centre

Add it then?

 

Think you are missing a trick, not using weather compensation and priority demand hot water.

 

[Nickfromwales]

It's an oil boiler? So zero modulation?

 

If you have a 230v signal that you want to connect to a zero volt arrangement you just isolate with a rely. £20 or so in TLC etc and job done.

 

Can you not energise the C of the timer from 230v L terminal, does the MI's not state this? Most are zero volt out of the box vs 230v out, so you can link L to C and energise the relay of the timer so it then gives 230v switched out.

[sb1202]

 

 

16 minutes ago, JohnMo said:

Add it then?

Cant. It's only for 3 zones.  

[ProDave]

14 minutes ago, sb1202 said:

 

 

Cant. It's only for 3 zones.  

One for HW, one for radiators, one for UFH.

 

If it can't do that, choose a different boiler.

[JohnMo]

27 minutes ago, sb1202 said:

only for 3 zones

 

56 minutes ago, Nickfromwales said:

oil boiler? So zero modulation

So maybe good reason it only does 3 zones.

14 minutes ago, ProDave said:

One for HW, one for radiators, one for UFH.

 

Otherwise lots of short cycling unless you are buffering to a big buffer or thermal store, which as you are S plan out most likely are not.

[sb1202]

1 hour ago, ProDave said:

One for HW, one for radiators, one for UFH.

 

If it can't do that, choose a different boiler.

Sigh.... read my OP.
Boiler is 2 ZONE s-plan pipe circuit. 
CH = ZONE 1.
UFH = ZONE 2
UFH ZONE = 5 ROOM ZONES which need an 8 ZONE wiring centre in order to accommodate wiring for 5 actuators, thermostats, zone valve etc,

The Navien wiring centre is a 3 ZONE wiring centre - which means it physically cant take all the wires for 5 actuators, thermostats etc 

I'm certainly not going to rip out a £6k bolier and replace it.  

[sharpener]

My reading of the drgs is that connecting the L or SL to the CH term of CONM4 is the call for heat from the Navien wiring centre. So wire your new UFH 8-way box to that either direct or with a £10 relay after checking what is going on with a neon screwdriver. E&OE.

[SimonD]

9 minutes ago, sharpener said:

SL to the CH term of CONM4

 

Yes this.

 

I'm really confused. The installation manual clearly shows switched live from wiring centre to boiler terminal 4 on CONM4. This is connected to the two orange switched lives that come from dhw and ch 2-ports, which is standard in the wiring centre. So to add ufh, there will be a switched live from the ufh 8 zone wiring Centre, which is sometimes volt free and just needs a bridge to com on the wiring Centre itself, and Bob's your uncle.

 

Given the thread, this seems too simple. Or am I missing something?

 

7 hours ago, ProDave said:

This is what happens often when a plumber connects something a little out of the ordinary, he does not understand it and cannot work it out.  (no offence to certain plumbers on here who are well capable of integrating different kit)

 

Some electricians too 😉 A customer of mine had new ufh installed while I was away last summer and then emailed me when i got back to say that neither the heating engineer nor his very competent electrician could get the ufh calling for heat to the boiler. It took 10 minutes 😁 I was tempted to say it was a very complicated and expensive call out but went easy on the electrician,  who was there when I sorted it 😀

[JohnMo]

8 hours ago, sb1202 said:

ZONE 2
UFH ZONE = 5 ROOM ZONES

Good luck getting that to run without a big buffer. Lowest boiler output is 17kW on any of the boilers in the range. And the lowest circulation pump flow rate is 15l/min. All 5 UFH loops will not support that flow rate on there own or all together. 

 

There is usually a good reason why boiler manufacturers don't want you trying to run lots of zones direct from their boilers, because they cannot modulate to small enough outputs.

[sb1202]

2 hours ago, JohnMo said:

 

There is usually a good reason why boiler manufacturers don't want you trying to run lots of zones direct from their boilers, because they cannot modulate to small enough outputs

We spoke with Navien and the plumber beforehand. They were given the UFH spec and they said it's no problem. The boiler can modulate to demand and the flow rates are set at the manifold per zone. If Navien had concerns, they would have told us. Thanks for taking the time to reply, but this is going off topic. 

 

[sb1202]

11 hours ago, sharpener said:

My reading of the drgs is that connecting the L or SL to the CH term of CONM4 is the call for heat from the Navien wiring centre. So wire your new UFH 8-way box to that either direct or with a £10 relay after checking what is going on with a neon screwdriver. E&OE.

That's my reading of it too. The problem is the drawings don't match the mainboard on the boiler. When we spoke with Navien tech about it, they walked us through and asked us to remove a jumper on the mainboard but when I said there was no jumper, they went "oh!".  I suspect the mainboard is a newer model and the manual refers to an earlier model. Waiting on Navien to come back to us meantime. As for the UFH 8 wiring centre, it's a nightmare. It has no branding, manufacturing batch number to go by. All I know is that it's a "Waterline" circuit board and there are different revisions of this particular circuit board and different manuals. As soon as Navien come back, I'll probably end up ditching the current UFH-8 wiring centre and buy a branded one.

 

11 hours ago, SimonD said:

Given the thread, this seems too simple. Or am I missing something?

See above. You're right, it should have been simple. 

[Huckleberrys]

I install naviens a lot, nice boiler. You just need a 240v signal to the switched live..use a relay if it's volt free from your wiring centre. It is a simple one. The jumper to remove will be between 4 and 5 on conm4

[ProDave]

8 hours ago, sb1202 said:

As for the UFH 8 wiring centre, it's a nightmare. It has no branding, manufacturing batch number to go by. All I know is that it's a "Waterline" circuit board and there are different revisions of this particular circuit board and different manuals. As soon as Navien come back, I'll probably end up ditching the current UFH-8 wiring centre and buy a branded one.

Nothing wrong with the UH-8 it does what it says and it provides a relay contact call for heat which can be wired as a volt free contact or a switched live, or anything else you care to imagine.  I would be very surprised if you went to the trouble of changing the UH-8 for something else if it would be any different.

[Nickfromwales]

21 minutes ago, Huckleberrys said:

I install naviens a lot, nice boiler. You just need a 240v signal to the switched live..use a relay if it's volt free from your wiring centre. It is a simple one. The jumper to remove will be between 4 and 5 on conm4

Is it an oil boiler that can modulate.............?

[Nickfromwales]

21 hours ago, sb1202 said:

Sigh.... read my OP.
Boiler is 2 ZONE s-plan pipe circuit. 
CH = ZONE 1.
UFH = ZONE 2
UFH ZONE = 5 ROOM ZONES which need an 8 ZONE wiring centre in order to accommodate wiring for 5 actuators, thermostats, zone valve etc,

The Navien wiring centre is a 3 ZONE wiring centre - which means it physically cant take all the wires for 5 actuators, thermostats etc

Ermmmm.....the installers knew this at the time I presume, and carried on anyways; knowing there were 5 actuators that needed to be connected (to a wiring centre that can take 5 Act's and 5 stat inputs per space).

 

Buy a 5 zone wiring centre, or is that somehow too easy and they don't make one (which would be ridiculous). Last house I moved people in to had 19 loops over 8 zones. Shirley, this manufacturer does bigger wiring centres?!?

[SimonD]

3 minutes ago, Nickfromwales said:

Ermmmm.....the installers knew this at the time I presume, and carried on anyways; knowing there were 5 actuators that needed to be connected (to a wiring centre that can take 5 Act's and 5 stat inputs per space).

 

Buy a 5 zone wiring centre, or is that somehow too easy and they don't make one (which would be ridiculous). Last house I moved people in to had 19 loops over 8 zones. Shirley, this manufacturer does bigger wiring centres?!?

 

TBH the installers could have made their life easier by just using a heatmiser UH-8 as that can also control rad ch and dhw, and then no need for the abovementioned Navien wiring centre which I assume is just like the widely used Honeywell and Drayton standard wiring centres. It would also be a lot tidier I think.

[Huckleberrys]

1 hour ago, Nickfromwales said:

Is it an oil boiler that can modulate.............?

It has a 2 stage burner, low flame and high flame...modulation of sorts.

[Nickfromwales]

29 minutes ago, Huckleberrys said:

It has a 2 stage burner, low flame and high flame...modulation of sorts.

AKA "Welsh modulation" lol  

 

It's a good boiler then, on paper, but I wonder how well it deals with particulate build-up if installed in a situation where its constantly low-flame and running a 'less-than-great' cycle pattern?

 

Oil likes to burn hard and strong, for a decent burn cycle afaik.

[Huckleberrys]

8 hours ago, Nickfromwales said:

AKA "Welsh modulation" lol  

 

It's a good boiler then, on paper, but I wonder how well it deals with particulate build-up if installed in a situation where its constantly low-flame and running a 'less-than-great' cycle pattern?

 

Oil likes to burn hard and strong, for a decent burn cycle afaik.

You don't want to miss a service on them, however nice and easy to flush through with a downward firing burner. All stainless also so very light. Only complaints I get sometimes is as a blue flame boiler they are noisier due to the fan blasting that air through.

10 hours ago, Nickfromwales said: