Help required wiring my ASHP/UFH

[joe90]

I am stuck regarding my ASHP and getting the UFH to work from it. Below is the wiring diagram for the Aeromax but I cannot see how the UFH pump can be wired to it, also I have a buffer tank for the UFH with a stat and not sure where the stat would be wired too. I bought a command unit which will programme everything (including the heat curves) so I should not need the timer or programmable stat. I am sure I am not the only one with a Kingspan Aeromax (carrier rebadged) ASHP . Ta

 

 

[PeterW]

I think from reading the manual, the UFH circ pump will need to be triggered from the room stat and the buffer stat will need to trigger the ASHP. 

 

That would mean the connection on 3/6 from the room stat would be the tank, and the programmable stat would just fire the circ pump. 

 

The downside is that it means the UFH could call for heat from a cold buffer, or wipe the buffer out pretty quickly if the ASHP is in DHW mode. 

 

You could use a zone valve with micro switch to trigger the pump too, or make it force the ASHP into HTG mode. 

 

I’m still trying to work out why the Timeswitch connects to 13 on the controller directly and via the stat as the info on the web is less than helpful !!

[ProDave]

I would not use a 3 port valve. Work of the devil in my mind. I would use separate 2 port valves, one for hot water and one for heating.  Without seeing the dull description of the valce wiring terminals you might need to add a relay to achieve that.

 

Once you have separate 2 port valves, it is then a simple matter of connecting the heating 2 port valve's switch contact (orange and grey wires) to turn on the UFH manifold and it's pump whenever the heating is on.

[PeterW]

2 minutes ago, ProDave said:

I would not use a 3 port valve. Work of the devil in my mind. I would use separate 2 port valves, one for hot water and one for heating.  Without seeing the dull description of the valce wiring terminals you might need to add a relay to achieve that.

 

Once you have separate 2 port valves, it is then a simple matter of connecting the heating 2 port valve's switch contact (orange and grey wires) to turn on the UFH manifold and it's pump whenever the heating is on.

 

You can’t do that with the Aeromax as it only controls the 3 port. It has no concept of zone valves and it controls the flow temps internally to the two separate circuits. 

[dpmiller]

Looking at he MIs, terminal 3 on the TS715 has no function, they're just using it as a junction.

Edited September 26, 2018 by dpmiller

[joe90]

I suppose you would not want the UFH pump to operate till the buffer was up to temp? I am hoping to not use the programmable stat or timer as I believe the command unit will do all this. ?

Edited September 26, 2018 by joe90

[ProDave]

6 minutes ago, PeterW said:

 

You can’t do that with the Aeromax as it only controls the 3 port. It has no concept of zone valves and it controls the flow temps internally to the two separate circuits. 

It's a personal thing, I dislike 3 port valves.  My LG heat pump was the same it proposed a 3 port valve to switch between heating and hot water but I used two 2 port valves instead.  When one is open the other is shut. Simple, and the separate feedback switches from each makes other controls easier.  I think most heat pumps only ever heat hot water, or heating separately, never together, because of the different flow temperatures.

 

But nothing wrong with doing as they say and using a 3 port.

 

I will let others who have done so advise on a buffer tank.

[PeterW]

19 minutes ago, dpmiller said:

Looking at he MIs, terminal 3 on the TS715 has no function, they're just using it as a junction.

 

Ok so I’d assumed it was a standard 2 channel timer, but looks like they are using it as a single to control the hot water only. 

 

These things must prioritise internally then as that’s a standard diverter valve not a mid position valve !! @joe90 was the 3 port supplied with the pump ..?? 

[joe90]

12 minutes ago, ProDave said:

It's a personal thing, I dislike 3 port valves.  My LG heat pump was the same it proposed a 3 port valve to switch between heating and hot water but I used two 2 port valves instead. 

 

I would rather not start taking the pipework apart again but I take your point on two separate valves.

 

1 minute ago, PeterW said:

was the 3 port supplied with the pump ..?? 

 

No, but on @Nickfromwales advise I got a valve that was either DHW or UFH and no mid point.

[PeterW]

4 minutes ago, joe90 said:

 

I would rather not start taking the pipework apart again but I take your point on two separate valves.

 

 

No, but on @Nickfromwales advise I got a valve that was either DHW or UFH and no mid point.

 

Ok so that’s a diverter then - all good !

 

What stat is on the buffer ..?

[joe90]

Here you go

 

 

[joe90]

Wot if,  I programme the command unit to deliver heating x o’clock till y o’clock at z temp, this will raise the temp of the buffer tank. If I then use the buffer stat set at say 25’ to switch on the UFH pump. This will then pump water round the floor only when the buffer temp is above the set 25’ (or any other temp that’s set?). If the buffer gets above 25’ then the blending valve will hold it to temp. ?

Edited September 26, 2018 by joe90

[joe90]

Right, been engaging the little grey cells and think I have come up with a plan, please comment.  The Kingspan control interface can act as the room stat and timer for heating which I intend to use. I can control the UFH pump with a timer (as long as it lines up with the controller or longer). Or, I could control the UFH pump with the stat on the buffer tank (with coil). If I do this the ASHP will heat the buffer tank and when it’s up to say 25’ the pump actuated, the ASHP will continue to heat the water up to the set max. The blending valve on the manifold will make sure the water stays below say 24’ (or whatever is set). This does mean the floor will continue to be heated after the heating has gone off till the buffer tank is reduced to 25’. Also the heating will be delayed on start up till the buffer tank is up to the set temp (but I guess this will happen with a buffer tank anyway).

 

DHW will be controlled by the tank stat and I will add a timer if we go E7 or E10.

 

The DHW tank came with two stats, lower and upper, I am thinking that if I wire a changeover switch between them I can control the amount of hot water heated, upper stat for the two of us, lower for a house full of guests!

 

Is this a good plan or should I go back to woodwork?.

[ProDave]

Do you have a UFH manifold controller of any sort? And are you heating it all as just one zone or a separate zone for each room?

 

I have opted for the conventional approach of one zone per room so each room has it's own thermostat, that is only 3 rooms in our case.  the UFH manifold controller starts the UFH pump when any one or more rooms calls for heat.

 

To me the logical control would be the same as you would have with a thermal store.  Keep the "heat in" and "heat out" as separate functions.

 

So "heat in" the ASHP will heat the buffer at any time until the buffer reaches it's set temperature. That's all it has to do. You can set on and off times using the heat pump's own controller if you don't want it on all the time. (no point in it being on and heating the buffer is say the UFH is off overnight)

 

"heat out" the UFH will run and draw heat out of the buffer at any time any room (may only be 1 "room") calls for heat.  You can use conventional time clocks for this function.

[joe90]

No, all one zone. I have got a Wunda thermostat controller with air temp and floor probe but Jeremy found the room (air) temp works best for his so I thought I would adopt this approach, the floor probe is there in case I need it. The command unit I bought (which also allows control of heating curves, whatever they are ?) can also act as thermostatic control and timer for heating. The command unit is in the cloakroom and the Wunda controller the hallway so not sure which would be best.

 

From reading the controller installation book the heat in is set to one temp and the heat out is set a different temp.!!!

 

i think that with our house I would heat in the early hours to make the house warm to wake up to (like our electric UFH and towel radiator in our en suite does) then heat again late afternoon for comfort in the evening. We get a fair amount of solar gain in the day. Also we may go E7 or E10 to benefit from heating and DHW during cheap hours .

 

i know that response times from the heating will be very slow due to the heavy weight house so it will take plenary of “suck it and see”.

 

P.S. just tried to start the UFH using immersion and found the plumber did not open the flow valves so floor loops still full of air! So need to bleed that lot ?

[ProDave]

For bleeding the floor loops you are best using a hose and bleeding each floor loop one at a time, with the valves to the rest of the system shut off.

[Jeremy Harris]

Just had a thought re: turning on the UFH pump.  The ASHP has a relay controlled output to switch an additional circulation pump, between terminals 12 (line) and neutral, all you need to do is wire the pump to this and then set the command unit to operate that relay.  The option for that is to go into the command unit installation menu and scroll to code 156.  There are three options, with the default being 1 normally.  The three options are:

 

0 - additional circulator remains off

 

1 - additional circulator ON/OFF cycle identical to the main pump.  The water pump works continuously in case of demand for hot water.

 

2 - additional circulator  ON/OFF cycle identical to the main pump. The pump is halted in case of demand for hot water.

 

The default setting should supplier power to the UFH circulation pump whenever the ASHP is turned on, which seems a reasonable option to me.  You will need to check that Kingspan have set up the programmed defaults to be the same as my Glowworm badged version of the same Carrier heat pump, but it's just a matter of going into the installation menu on the command unit and scrolling through to see what code 156 is set to and changing it if need be.

[joe90]

Star man, just checked and mine is command 157. Slightly different, 0 = always off. 1 = on/off depending by EHS on/off status. 2 = always on.  I thought the external heat source was to stop defrosting? So perhaps 1 = pump fir external warm water to defrost it?? . So 2 will Work which is the default.

 

i am confused tho as command 155 indicates the main water pump is set to depend on EHS being on 

 

(I prefer woodwork ?)

 

Edited September 29, 2018 by joe90

[Jeremy Harris]

Looks like it's 156 for yours too, but it has an additional use as a trace heater power source which isn't mentioned in my manual.  This is the section from my manual that shows pretty much the same selections:

 

[joe90]

Ah yes, oops thanks Jeremy.

[joe90]

Right , UFH working (temporarily using immersion in the buffer and pump on permenantly), nice warm floor but a few questions. The TRV on the manifold has a curly wire to a probe that fits in a socket on the top of the manifold (as below) the probe is a loose fit in the pocket, is this right? Will it register the correct temp if not a friction fit?  Also the TRV when set at its lowest ( * ) the top rail temp shows as 25”. Is there a better TRV (I think PeterW was getting one). When I contacted Wunda about this they did not show any interest (don’t think they understand passive house principle).

[Jeremy Harris]

The probe isn't a very tight fit inside that pocket, but seems to work OK as it goes in a fair distance.  25 deg C is about as low as that Wunda thermostatic valve will reliably go.  I found that I could get mine to go down to about 23 deg C, but it wasn't great at controlling the temperature when down that low.  25 deg C should be fine, I now run our system with about that flow temperature and it seems to control reasonably well, with just a small amount of overshoot above the set room temperature, which you can see on the data that's logged, but can't subjectively feel in the house.

 

I ended up replacing the UFH on/off valve at the other end of the manifold with a Salus stepper motor driven one, as in this post:

 

This is the valve: https://salus-controls.com/uk/product/thb23030/#description

[joe90]

Thanks Jeremy, I will get the ASHP up and running and see how it goes, if necessary I will get one of those balancing valves, they do seem very good.

[Jeremy Harris]

Just found out why the Salus motorised UFH actuator works so well on our system.  The headline temperature differential that it tries to maintain between flow and return is 7 deg C, which is higher than the differential we see on our system, and something I'd just put down to manufacturing tolerances.  I've just read the detailed technical stuff on this actuator and it seems that it reduces the temperature differential that it tries to maintain to 4 deg C when the flow temperature is below 30 deg C.  That's just about perfect for our needs, and explains why it works better than I thought it would.  The main reason I fitted it was because it has a much faster actuation time than the thermal actuators.  It's a real bonus to find that it also does such a good job of controlling a low power UFH system.

[jack]

17 hours ago, JSHarris said:

Just found out why the Salus motorised UFH actuator works so well on our system.  The headline temperature differential that it tries to maintain between flow and return is 7 deg C, which is higher than the differential we see on our system, and something I'd just put down to manufacturing tolerances.  I've just read the detailed technical stuff on this actuator and it seems that it reduces the temperature differential that it tries to maintain to 4 deg C when the flow temperature is below 30 deg C.  That's just about perfect for our needs, and explains why it works better than I thought it would.  The main reason I fitted it was because it has a much faster actuation time than the thermal actuators.  It's a real bonus to find that it also does such a good job of controlling a low power UFH system.

 

This is very useful info Jeremy, thanks. I'd been scratching my head about how it worked so well with such a large temperature differential when supplying relatively low temperature water from the ASHP (or buffer).

 

In my system, at 25 deg C supply temperature (the lowest my ASHP will output) this valve wouldn't open until the return temp is 18 deg C, which would be way too low. 4 deg C is a lot more sensible.

 

A version of this valve with an adjustable temperature differential would be excellent.