programmable UFH controllers

[vivienz]

I have UFH in my slab and upstairs but as yet have no controllers connected. I understand that I need programmable controllers - can anyone recommend any for this purpose?

[ProDave]

Can you post a picture?  Do you even have actuators on the manifold yet?

 

What do you want to achieve? That will determine what controller(s)

 

I opted for the simplest system (I like simple)  I have a simple and cheap manifold controller.  Each room just has a room thermostat, and the whole thing is under the control of one conventional central heating programmer to determine when the heating is on and off.

 

You can be more clever if you want to and have programmable thermostats so you can set different rooms at different temperatures at different times.

 

Without a controller, what powers the UFH manifolds pump?

 

This is the only picture I have to hand of mine, showing the bargain basement controller, but before I had attached and wired the individual actuators (in fact before I had connected any pipes!!!)

 

[vivienz]

Apologies, Dave. What I meant to say was room thermostats that will control the call for heat. Currently, the full ground floor heating can be on or off but no control over the temperature. Everything that is down the line from the room thermostat is in place.

I should add that I won't be installing these myself but will have an electrician put them in.

Thanks.

[ProDave]

Post a picture of what you have as that will influence what will work with it or not.

[Adrian Walker]

 

2 hours ago, vivienz said:

Apologies, Dave. What I meant to say was room thermostats that will control the call for heat. Currently, the full ground floor heating can be on or off but no control over the temperature. Everything that is down the line from the room thermostat is in place.

I should add that I won't be installing these myself but will have an electrician put them in.

Thanks.

 

 

It's a very interesting question in an almost passive house and one that has MVHR.  Would you like one room/zone to be warmer than another?

[ProDave]

2 minutes ago, Adrian Walker said:

 

 

 

It's a very interesting question in an almost passive house and one that has MVHR.  Would you like one room/zone to be warmer than another?

Probably not. Indeed many on here just have the whole house as one zone.

 

I have 3 zones downstairs and they all pretty much turn on and off together, so there is not much benefit to be had. But on the other hand it is not hard or expensive to zone the house a bit.

[Jeremy Harris]

I've found that zoning doesn't really work effectively in our house, so I have all our UFH zones running as if they were just a single zone.  The whole lot is controlled with a simple room thermostat in the hall, plus a simple programmer that is set to turn the whole system on or off.  Seems to work OK, and is easy to use, as the controls are simple (I like simple...).

[Temp]

Think about what features you want. At the very least I would want stats that can handle the clocks going forwards and back automatically but perhaps you also want to be able to change settings while on holiday using your mobile phone?

 

You also need to know if your wiring centre needs 12V or 230V stats? I think most are 12V but not all?

 

Our UFH stats can be set to four different temperatures per day which we typically have set to..

 

Waking up 21c

Daytime 18c

Evening 21c

Night 16c

 

The time at which it changes temperature can be altered as well as the temperature. You can also have a different set of times and temperature s at the weekend (eg if you get up early or want it warmer in the daytime).

 

Do you have separate zones/loops for the bathroom? If so companies like Heatmiser do a stat with a remote sensor. Sensor goes in the bathroom, display panel goes outside bathroom door (to avoid damage by high humidity).

 

 

[vivienz]

Sorry for the delay in posting pics here, Sunday lunch for the outlaws gets longer every time; it will extend into a candlelit supper before long (on Royal Doulton china with hand-painted periwinkles, of course).

 

Anyhow, these are photos of the ground floor UFH manifold and the gubbins in the garage, including the willis heaters.  I believe that the UFH circuit isn't commissioned yet, in so far as the pump isn't wired up and the pipes need bleeding, so it's just the ground floor for now.  I'm not sure how much longer the house will remain at a comfortable temperature so I need to get the room stats sorted asap.

 

 

[dpmiller]

how will you bleed the air out of the Willis?

[Jeremy Harris]

The UFH is configured to all be a single zone (no actuators on the lower, return, manifold) so all you need to control the UFH is a programmable room stat.  Plenty of choices, depending very much on what features you want.  At the most basic I'd go for a programmable stat that automatically changes the clock, as @Temp, suggests (although it does seem possible that we might do away with the BST/GMT change twice a year). 

 

You could go for something "smart", that can be controlled by an app, although there's always the risk that any app-based control system could fall over as devices get upgraded, cloud-based infrastructure falls over, etc.

 

If you want to consider zoning the UFH, then the white caps on the return manifold need to be swapped for actuators, and the actuators need connecting to a wiring centre, that then allows individual loops, or groups of loops, to be independently controlled.  This means more thermostats, to set the temperature for each zone, and may or may not also need a programmer that can control the overall timing of when things are on or off.  This is potentially a fair bit more complex, and needs a bit of thought as to whether it will be a benefit.  That really depends on how well heat can move around the house.  For example, we have no heating upstairs, other than towel rails in the bathrooms.  Despite that we sometimes find that the bedrooms get a bit warm.  If we had zoned heating that would still happen.  It might be an idea to have the bathrooms separately controlled, though, as being able to warm the bathroom floor slightly morning and evening is a nice feature to have.  You might want to think about having maybe three zones, one for the bedrooms, one for the bathrooms and one for the rest of the living areas.  It depends very much on how you like things.  We like the bedrooms to be cooler than everywhere else, so are happy with only heating the ground floor living areas, but we're all different!

[Jeremy Harris]

4 minutes ago, dpmiller said:

how will you bleed the air out of the Willis?

 

Looks like there's an AAV above the Willis heaters, on the flow side.

[dpmiller]

1 minute ago, JSHarris said:

 

Looks like there's an AAV above the Willis heaters, on the flow side.

 

which leaves a big air pocket above the side tapping. They're normally fitted the other way up round these parts...

[vivienz]

Thanks, chaps. The bathrooms aren't in the wet UFH loop, I have electric UFH mats and heated towel rails, although there are no elements in the towel rails yet, so the bathrooms will be okay once this is done.

I don't mind not having the downstairs heating zoned - there's not much point as far as I can see, but I would prefer the upstairs to be zoned as one of the rooms is my office/sewing room and I don't want to get chilly in there.

For the downstairs, then, I'm okay to get hold of some programmable thermostats (not interested in smart ones) and get them wired in, from the sound of things, and that will at least sort out the ground floor.

 

[Ed Davies]

31 minutes ago, JSHarris said:

Looks like there's an AAV above the Willis heaters, on the flow side.

 

Looks like the forum software has “helpfully” inserted the wrong hover text on AAV here. I'm pretty sure Jeremy means Automatic Air Vent, not Air Admittance Valve.  A Air Vents let air out, A Admittance Valves let it in.

[Jeremy Harris]

I found it best to use thermostats that can be set to have a small switching hysteresis, as it's a bit too easy to get significant over/under shoot with thermostats that have, say, a 1°C hysteresis.  I fitted Computherm wireless stats, that can be set to switch with a 0.1°C hysteresis, and they seem to work well.  Not sure if they do a programmable version that adjusts for BST/GMT though.  Wireless stats are the easiest to fit, as the only wiring is near the manifold.

[vivienz]

In the near constant temperature world of UFH and a highly insulated building, does the GMT/BST thing matter?

[PeterW]

13 minutes ago, vivienz said:

In the near constant temperature world of UFH and a highly insulated building, does the GMT/BST thing matter?

 

Only if you’re using E7 and want to make sure you take your E7 usage to the wire as they use GMT time clocks so you need to be careful with the shoulder hours. 

[Jeremy Harris]

6 minutes ago, vivienz said:

In the near constant temperature world of UFH and a highly insulated building, does the GMT/BST thing matter?

 

 

Depends on whether you want to take advantage of an off-peak tariff, like Economy 7, really.  I have our UFH set to charge the slab up overnight, at the cheap rate, and unless it's really cold we don't need to boost it during the day.  Doesn't make a massive difference, in the overall scheme of things, as the heating energy use is so low that the cost saving is probably less than the cost of an evening out at the pub for dinner.

 

I sometimes think I've spent far too much time and effort thinking about optimising stuff to the last few %, when in reality I'm not sure if it really matters if our annual heating bill is £100 or £200.  It's pretty modest in the overall scheme of things, certainly when compared to the ~£1150/year we spent on heating and hot water at the old house.

 

You could just not bother with programmable thermostats, run the system all the time, and have the temperature set by a few room stats.  Given the pretty slow thermal response of your house (I'm guessing it'll be similar to ours) it should just stay at pretty much the same temperature all the time with such a system, barring a bit of solar gain warming things up a bit.

[joe90]

After reading @JSHarris blog who reverted to a room stat after spending loads of time with his “smart” UFH programming I also decided to go “KISS” (keep it simple stupid). I also dislike lots of tech as it’s more to go wrong and quickly becomes obsolete. I have just one zone, downstairs, and a room stat in the hallway. I have upped the flow rate into the lounge as I want a slightly higher temperature in that room and the heating runs 24/7 (via a buffer tank to stop cycling). On the horizon is going E7 or E10 as I believe the slab and DHW tank heated over night would be sufficient to heat our “heavy” house for a 24 hour period. I have a room stat supplied by Wunda who supplied all the UFH kit but the hysteresis is too high and I need to change it out like Jeremy said above.

[ProDave]

On the subject of hysteresis.  I still say a good mechanical thermostat, providing it is wired properly (3 wires) so the "accelerator heater" works as designed, has very little hysteresis and does a good job of maintaining our house at a constant temperature.

[joe90]

5 minutes ago, ProDave said:

On the subject of hysteresis.  I still say a good mechanical thermostat, providing it is wired properly (3 wires) so the "accelerator heater" works as designed, has very little hysteresis and does a good job of maintaining our house at a constant temperature.

 

Oh, I find the mechanical thermostat on my DHW cylinder does not have a small hysteresis, (and it only has two wires) what’s this three wire business Dave.???

[ProDave]

17 minutes ago, joe90 said:

 

Oh, I find the mechanical thermostat on my DHW cylinder does not have a small hysteresis, (and it only has two wires) what’s this three wire business Dave.???

On it's own, a mechanical thermostat has huge hysteresis.

 

They overcome this with an "accelerator heater" which is a posh name for a tiny (and I mean tiny) heater inside the thermostat.  This is usually just a small resistor.  The "accelerator heater" is turned on when the thermostat is "on"

 

So your heating is on, the accelerator heater is on, so the local air inside the thermostat is slightly warmer than the room air.  The thermostat is calibrated to allow for this.  So the thermostat switches off at say 20 degrees.  the accelerator heater goes off and the local air is no longer heated. So the air inside the thermostat cools to room air temperature.

 

By doing this, as long as the accelerator heater is sized to uplift the internal temperature by an amount equal to the hysteresis, then you have eliminated that hysteresis.

 

So as well as live in, and switched live out, you need the third wire connected to neutral, just to power the little accelerator heater when the thermostat is on.

[joth]

15 hours ago, vivienz said:

Thanks, chaps. The bathrooms aren't in the wet UFH loop, I have electric UFH mats and heated towel rails, although there are no elements in the towel rails yet, so the bathrooms will be okay once this is done.

I don't mind not having the downstairs heating zoned - there's not much point as far as I can see, but I would prefer the upstairs to be zoned as one of the rooms is my office/sewing room and I don't want to get chilly in there.

For the downstairs, then, I'm okay to get hold of some programmable thermostats (not interested in smart ones) and get them wired in, from the sound of things, and that will at least sort out the ground floor.

 

 

I've also been thinking about this need for a single "boosted" zone (study, or elderly guest bedroom) but it requires not one actuator on the manifold for that loop, but to install the other N-1 (so 8 in @vivienz's case above) actuators for all the loops you want to shut off when running the single boosted zone.... Which adds quite some complexity and cost to a otherwise simple idea. 

As our UFH is only downstairs I think we'll start with no actuators and run it as one zone, see how it goes. 

[vivienz]

1 hour ago, joth said:

 

I've also been thinking about this need for a single "boosted" zone (study, or elderly guest bedroom) but it requires not one actuator on the manifold for that loop, but to install the other N-1 (so 8 in @vivienz's case above) actuators for all the loops you want to shut off when running the single boosted zone.... Which adds quite some complexity and cost to a otherwise simple idea. 

As our UFH is only downstairs I think we'll start with no actuators and run it as one zone, see how it goes. 

 

That makes sense. The system has been designed to have zoned heat as, otherwise, what's the point of thermostats in each room rather than one single one for everywhere. The hardwiring is in and I currently have cables dangling out of the walls next to the light switch in every room.