SSR query

[BotusBuild]

We have an electromagnetic relay in our heating circuitry that was purchased at short notice so I was not able to research. It has a very annoying loud click. It's inside an enclosure in the plant room behind a solid door.

I want to replace this with a silent SSR. The control and load are both AC.

The load, a circulation pump for the UFH, is a Stuart Turner Pulse OEM 25-60/130, with a power consumption of 4.5 to 38W, which I work out to be <0.2A current draw.

 

Will the 10AA version of this SSR be OK? 

 

[JohnMo]

Why do you need a SSR to drive a circulation pump?

[-rick-]

27 minutes ago, BotusBuild said:

Will the 10AA version of this SSR be OK? 

 

Not an electricitian but I would say no. Will it work? Maybe (what is your switching voltage?). Is it compliant with regs, no, at least not without building an enclosure for it, etc, etc.

 

@JohnMo asks a good question, there may be alternative options to give you what you want.

 

The existing relay you have is pretty beefy. One option is to look for a smaller relay from the same line as existing (will likely make less noise when switching), otherwise look for a DIN rail mounted SSR but if you want to pass electrical inspections in future then even then need to be careful with the details to be compliant (hopefully an electrician will be along to say more).

[BotusBuild]

45 minutes ago, JohnMo said:

Why do you need a SSR to drive a circulation pump?

Well, as stated, I want to replace the noisy electromagnetic one.

 

Now, if your Q is "why do you need a relay", then the answer to that is "that's what the electrical wiring diagram called for".

[ProDave]

Most people don't have any form of relay in their fuse box to turn the heating on or off.  So can we get to the bottom of why you have one, and what generates the trigger signal to turn it on or off?  And how often does it turn on and off?

 

A SSR probably could technically be used but the question remains why?  Not something most heating systems need.

[Alan Ambrose]

Re SSRs - suggest din mounted and a brand name - meanwell, xpower etc (the kind of thing you could purchase from RS) - the off-brand ones tend to be a bit dodgy.

[BotusBuild]

So, this has been my thinking all along. I did question this with the installers at the time, but I think they were less than receptive after I had already pointed out a mistake that they had to rectify.

 

The setup is as follows (and the more I look at the detail, the more I am concerned):

 

Vaillant heat pump providing for DHW and UFH. DHW is a 250L UVC and is working well. There is a Vaillant appliance interface (VWZ AI) and a SensoComfort (VRC 720/3). The first has all the wires and the latter is the how you do the settings.

 

The UFH  starts with a four port buffer tank fed from the ASHP. On the hot output is the circulation pump that pushes water to the UFH manifold. Each loop has a valve connected into a TIO 8 channel wiring centre, and we have one thermostat currently. Effectively we are running a single zone and I have actually left all the valves "open".

 

With this setup, I would be looking for the UFH wiring centre to be controlling the "call for heat" to the heat source. As we have it physically setup, that heat source is via the buffer tank and so the wiring centre should send a signal to the circulation pump to turn on and send hot water to the UFH manifold.

 

Wiring:

 

From the installation instructions for the Vaillant interface, EVU is stated to be the Energy Supply Company contact. No idea why this is wired in as it is.

From the installation instructions for the TIO wiring centre, Valve is supposed to be interfacing with a UFH Valve. There is a connector labelled Pump, with a L and N terminal. 

 

My plan is to attach a meter to the Pump connector, and turn the thermostat up to call for heat and see if there are volts on this connector. If so, surely the Pump should be connected to this directly?

 

Edited Saturday at 15:00 by BotusBuild

[ProDave]

6 minutes ago, BotusBuild said:

 

Looking at your diagram, the wiring centre IS providing Switched L and N to the pump. and A1 and A2 on the relay is the relay coil.  So the relay turns on when the pump is running.  3 and 4 are a normally open contact on the relay.

 

So the relay is NOT switching the pump, it is providing a volt free open / close contact to the EVU

 

This relay should not be necessary as most UFH controllers will already provide a volt free contact of some sort often labelled as boiler or call for heat, which will provide this volt free contact without needing the relay.

 

Can you post a manual or a close up picture of the connections available for your UFH controller?

[JohnMo]

Pretty poor install really. Why a buffer at all, if you are running single zone? Then you can delete the interface, the secondary pump, all the actuators on the UFH manifold. Either bypass the buffer totally or convert to a volumiser (I would convert to volumiser as you have it).

[BotusBuild]

@ProDave, Is this what you are asking for?

 

https://tioclimatesolutions.co.uk/wp-content/uploads/2023/12/TIOWIR0004.pdf

[ProDave]

19 minutes ago, BotusBuild said:

@ProDave, Is this what you are asking for?

 

https://tioclimatesolutions.co.uk/wp-content/uploads/2023/12/TIOWIR0004.pdf

Yes.

A screen grab of the important bit 

 

 

The red and blue wires shown here going to the boiler are a volt free normally open contact that does exactly what your relay is doing, closes when the UFH pump is on.

 

Ditch your relay and connect the Red and Blue shown here to the EVU

[BotusBuild]

Thank you @ProDave.

 

Should I leave the circulation pump connected to the Valve terminals? Or move them to the above Pump terminals?

[ProDave]

5 minutes ago, BotusBuild said:

Thank you @ProDave.

 

Should I leave the circulation pump connected to the Valve terminals? Or move them to the above Pump terminals?

Yes move that to the pump terminals.

 

It's as if the installer did not have, or could not read the very clear wiring instructions.  Or simply did not understand them.  Sadly I have found several UFH installs where the installer did not have a clue how to connect them properly.

[BotusBuild]

I will make these changes in the next couple of days and report back. Thank you again.

[sharpener]

EVU is the standard way of controlling the HP from a third-party device when the HP system itself doesn't have multiple zones (for these you need a VR70 or 71 Wiring Centre with its own call for heat inputs).

However many ppl here and on the Vaillant Arotherm + FB group would say you will achieve a higher CoP by using the room stats only to set an upper limit (try 25C to start with) and only bring them into play if particular rooms are still too hot after you have optimised the weather compensation.

 

3 hours ago, BotusBuild said:

Should I leave the circulation pump connected to the Valve terminals? Or move them to the above Pump terminals?

 

Neither, the Vaillant-approved schematic for yr setup has the volt-free contact from the UFH going to the EVU input but the pump should be run off the MA1 terminal on the VWZ AI and controlled by the HP directly.

Schematics here https://www.facebook.com/groups/488794632317506/permalink/1072492593947704/, I think you need the one on p6. There is also a recent discussion on the use of MA1 on the same FB group.

 

ETA also with a buffer you need basic System Diagram code 10 not 8 in the setup menu.

 

 

Edited Saturday at 20:39 by sharpener

[BotusBuild]

Thanks @sharpener. On those schematics (3 pages), it shows the connection to EVU from the UFH wiring centre coming through 12s which is shown on the 3rd page as "DPDT relay (3rd party)".

 

I think this is what our installer has put in (a double pole, double throw relay), on the basis we were installing another UFH manifold with a similar wiring centre setup (2nd manifold added but not the wiring centre, and unlikely to fit this). However, they've obviously got the pump wiring wrong.

 

I will follow your advice above first (losing the installed relay along the way) and see how we get on.

[BotusBuild]

Update (summary - pump running constantly!):

Boiler COM and NO (normally open?) now connected to EVU 2 and 1 respectively (see pics)

 

Pump connected directly to MA1.

2

 

PROBLEM: The pump (the one after the buffer tank) is on all the time whether the stat is set to require heat input. So, whether the wiring centre is calling for heat or not the UFH circulation pump is running.

 

Settings which I think are relevant:

 

Anyone shed any light on why the pump is always running.

[sharpener]

1 hour ago, BotusBuild said:

Anyone shed any light on why the pump is always running.

 

Things to try:

• Have you followed all the settings on the 3rd page of the relevant schematic, in particular system diagram set to 10?
• However I am not sure about connecting to MA1 anyway as I can't see a way of configuring it in the black controller menu using this simulator (https://simulator.vaillant.com/vrc720/at/#/simulator). But there is this in the white controller manual though none of these options seem appropriate for yr system:

• You could alternatively connect to MA2, with the right choice of option, IIRC it is set by default to HW circulation which is not what you want, try Zone

 

 

• Alternatively you can leave it on hw but set up a time schedule, which is not as good as having it follow the demand but better than having it running 24/7

 

Try posting a query on the Arotherm + FB page, there is a lot more expertise to be found there though unfortunately a lot of BS as well.

Edited 18 hours ago by sharpener

[BotusBuild]

51 minutes ago, sharpener said:

Have you followed all the settings on the 3rd page of the relevant schematic, in particular system diagram set to 10?

Yes, it is

 

I've just posted on the FB page and will see what is said before trying anything else but thanks for the response.

[JohnMo]

You have paid someone a small fortune to install this, get them to sort, stop messing.