Looking for suitable 2 coil relay 2 pole relay to fix C plan boiler control issue

[cliffa]

Hi, in my new home I inherited a non fully functioning Baxi gravity HW pumped CH system. There was a 2 port Sunvic valve in the gravity feed that had no actuator fitted and was seized solid in the open position. There was no tank stat fitted either.
I wanted to gain control of the cylinder HW temp and so decided to replace the Sunvic ML 3501 valve like for like and obtained both MOMO SZM1801 and Spring Return SZ2301 Sunvic Actuators (it was cheaper to by the valve body and spring return actuator complete).

I decided on getting the Honewell Y9420S Sundial RF Pack 3 for controller with wireless room and tank stats.

I've discovered now that I'm going to need to fit a relay solution so as to be able to either independently control firing the boiler or ensure the pump is only powered when the CH calls for heat. There aren't sufficient wires / contacts on the Sunvic actuator to do this. My initial thoughts are to use a relay with 2 solenoid windings so either the HW or CH control can fire the boiler. I could use two separate relays but ideally I'd like to use a relay with 2 windings. Any other suggestions gratefully received.

 

[Hugh Jaleak]

Sounds complicated. Why aren't you using a standard 'C' plan wiring setup?

 

[cliffa]

Hi Hugh, I guess I didn't research things quite as thoroughly as I should in the first place. I decided replacing the original sunvic 2 port valve would be the easiest solution from a plumbing point of view. It is fitted in the small space inside the chimney cavity by the back boiler so not easy to get to to re-work any pipework. I selected the Honeywell programmer as it looked like it should do the job. The sunvic actuator though only has 4 wires (missing the white wire) and not 5 shown for the honeywell V4043H depicted in the C-Plan diagram. It will be this white wire that carries the CH demand to the actuator and back out on the orange to the boiler. I should be able sort it with an external relay, just looking for recommendations. Many Thanks

 

[oilhead]

Drayton used to make these items, model RB2, but I've not seen one for years. Converting to fully pumped with either one 3 port or 2 2port valves will be much more efficient than retaining gravity hot water.

 

[cliffa]

Hi oilhead, thanks for the reply. From the diagram I've found the RB2 looks to only be a single coil device. http://www.global-download.schneide...e5e9ec852578a8006595fc/$FILE/DS21686_1205.pdf . It would be way too expensive as well. Under normal circumstances I'd agree I'd rather convert to fully pumped. But I'll leave that until the boiler needs replacing, which I hope isn't any time soon.

 

[bernardgreen]

Two of these relays and sockets

Finder_DIN_base

• bernardgreen
• 8 Nov 2015

fitted on the DIN rail in one of these

https://www.tlc-direct.co.uk/Products/WYESE2.html

will do what you need ( I think )

 

[cliffa]

Hi Bernard, yes I think you are right 2 x single pole relays are going to work out cheaper and easier to source. I've deciphered that the relay in the picture is a Finder 40.61.8.240.0000 which is stocked by Farnell in UK. The DIN rail holder strangely Farnell has to ship in from the US so attracts a high postage charge. I'll do some more searching for stockist unless you have a recommendation. Thank you very much.

 

[bernardgreen]

JPR electronics
https://www.jprelec.co.uk/store.asp/c=765/DIN-rail-sockets-for-40-Series-Relays

Don't forget to get the correct voltage coils.

Finder also do indicators that plug into the socket to show if the relay is engergised.

There are two pole versions of the same relay.

https://www.jprelec.co.uk/pdffiles/820-538d.pdf

 

[simond]

Eh? Wylex box is £2.40 and has a DIN rail in it so would it be sensible importing one from the USA?

Wylex also do the relays to put in them, but they call them contactors. Heating trades use this stuff all the time, although not for the task you've described.

 

[cliffa]

Hi Simon, I might have not been clear, I've ordered the Finder relays and DIN mountings from Farnell - I've gone with a 95.95.3 mount which I hope is OK as that one is held as UK stock. I've reserved the Wylex DIN rail box from TLC. Whole lot should come to about £24. I've had a quick look and the Wylex contractors are about £24 each.

 

[Agile]

I would have used one relay with a DC coil and used diodes to allow either supply to actuate the single relay.

But two relays are easier to implement as it does not require an understanding of diodes.

 

[DP]

will get back to you soon on easy solution. No diodes or DC supplies needed.

 

[jackthom]

Can't find a very clear diagram of the Sunvic internals. Is there no microswitch contact at all provided for when valve is open?

(Maybe better if Live, rather than CH ON, used to feed relay contacts.)

Not a great deal of use if there isn't a microswitch in there.

 

[DP]

Danfoss HPA2C has a SPDT switch while HPA2 only had orange and grey wires
Momo valve- earlier version needed dedicated power to open and close the valve but current version absence of mans drives th valve to close position

Using HPA2C actuator you will not need a relay
Using HPA2 a relay will be needed so above diagram appropriate

For HPA2C
Connect common to boiler
NO connected to 240 volts so when hw MV opens and boiler runs
Pump connected to NC. Thermostat SL to NC and CH aux switch powers room thermostat. If heat call made at clock, MV opens and pump and boiler run only if roomstat calling

 

[D_Hailsham]

Have you actually installed the Sunvic Valve? If you haven't, take it back to the shop and ask them to exchange it for the Honeywell V4043H. Saves all the hassle of relays etc.