Underfloor heating zone valves with heat pump
So first of all, I'm based in The Netherlands, probably worth mentioning since wiring and heating systems might be slightly different.
Anyway, we've recently moved to a new house with a heat pump system and underfloor heating throughout the house. I've checked and the Vaillant heat pump we have is compatible with the Tado Heat Pump Optimizer X.
Our underfloor heating consists of 2 dividers (or how do you call them in English?): 1 downstairs and 1 upstairs. Downstairs has 12 valves, upstairs 9 valves. Most valves are motorized valves connected to a room thermostat. That room thermostat is just an upper limit, so if I set it to 21C and it's 19C in the room, it'll open the valves, as soon as it reaches 21C it closes the valves. But it does not control heating request from the heat pump system, which is only controlled by the Vaillant sensoComfort thermostat in the living room.
As you can imagine, while it's broadly speaking working decent enough, some rooms are a bit colder than we would like.
So my idea is to use a Heat Pump Optimizer X and combine that with a Smart Thermostat X for each room to control the valves. However, I'm wondering:
- Is it a good idea with a heat pump system to introduce such zoning? Can it handle just heating 1 or 2 rooms as opposed to the whole house?
- Can I connect a Tado Smart Thermostat X to the 230V wiring that the current thermostats use? I'll explain the wiring below.
- If I do all this, can the Tado Smart Thermostat in each room actually request heating from the heat pump regardless of the temperature in the living room (where the main heat pump thermostat resides)?
Wiring for the thermostats to the underfloor heating zone valves is as follows:
P = black = switch wire
L = brown = phase wire (live)
N = blue = neutral wire
Basically, it's a simply NO relay system, if heating is required the valves are kept open, if heating is not required, the valves are closed.
I've seen pictures from years ago with the older V2/V3 thermostats that show the live wire going into COM, the switch wire into NO and the neutral wire into P1.
Would this work?
Comments
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I have v3 for few weeks and algorithms for ufh are abysmal, I would made sure it's Tado that you want.0
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@AddVariety
Some notes,
* what you call valves we call actuators.
* what you call dividers, i believe we call zones ( which funnily enough are opened and closed by what we call motorised valves)
At first glance there's nothing which worries me about your high level approach. Could you respond to these questions?
1. How many actual wall thermostats do you want in the first floor, and, seperately, in the second?
2. If you were to fit these to work in simple on-off or relay mode would you be aiming to connect each thermostat to the actuator that opens the underfloor supply to that room? And if so, what voltage do those actuators run on? 24volts? 230v?
3. So would that mean you would have a total of 20 or perhaps 22 wired thermostats?
In that model it would create:
* Two zones.
* One zone would have 9 logical rooms, the other would have 12 logical rooms. * On one floor one of the thermostats would be assigned as the zone controller, directly opening the valve for the floor. The same concept would apply on the other floor.
* They would link and if either demands heat, that would present a request to the heat pump.0 -
@Irek85
Would you mind starting another thread describing your challenges with Tado on a UFH environment? I have UFH in my home run by V3+.
Perhaps we can help? Like you most of us are just end users, nothing to do with Tado.0 -
@policywonk
Well, I assumed it's not my individual issue. But perhaps you are right and I'll start new discussion. Just please let me know (regarding ufh zones) - does early start works for you and does Tado stop heating after reaching desired temp?0 -
@policywonk Thanks for the notes, English isn't my native language so especially those terms are unknown to me, so always great to learn what those are actually called. ;)
Regarding your questions:
- I'd want 4 wall thermostats on the second floor and 3/4 wall thermostats on the first floor. Right now we have 4 (basic) wall thermostats on the second floor, one for each bedroom. On the first floor we basically have two: the Vaillant sensoComfort in the living room (which is an open space with the kitchen in a U shape) and the same basic thermostat that we've got upstairs for the home office. Ideally I'd like to add 2 additional wireless thermostats for the kitchen and living room area (those combined are about 70m2).
- Yes, I'd be aiming to directly control the actuators that opens the underfloor supply to that room. That's how it's currently hooked up with the other basic thermostats as well. Some of those wall thermostats control 1 actuator, some 3 at the same time. These are all 230V.
- In our case, in the ideal scenario, we'd use the 4 wired wall thermostats on the second floor and a total of 4 (wired/wireless) wall thermostats on the first floor. So 8 in total. This is because most thermostats control 2 or 3 actuators. For example: our kitchen and dining room (all open space) uses 3 floor heating zones so to speak, so 3 actuators, the living room 4, all bedrooms use 2 except for 1 that's significantly smaller and uses a single actuator.
I understand the rest of your explanation about zoning, however, I don't think the underfloor heaters have a valve in them. Would that pose a problem? I know my previous home did have that, which was indeed hooked up to the thermostat (later Tado V3), but there we had radiators in the bedrooms and only underfloor heating downstairs.
If I looked correctly in both the technical documents I have for the underfloor heating system (the design) and physically, I can't see a valve right before the zone (what I call divider). Here's a picture of one:
This is the second floor zone and those 7 actuators are linked to a total of 4 wall thermostats. The one that's not hooked up is the hallway.
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@AddVariety Its fun working with language. The charity where we volunteer has many, really lots, of Dutch people visiting the UK every month to help out with building repairs and with the mental health work the charity does. So genuinely fun to work with the vibrancy of Dutch people!
Moving on.
- Wired Tado thermostats are easy to fit in and replace others. Just count them up and start arranging the wiring in your walls to prepare to fit them. Those white plastic valves with blue leds, we call actuators in the UK.
- If you need to save money on the cost of wiring and making good, here is an idea. Tado has a concept of proxy controllers. One can fit a wireless smart thermostatic sensor in one room and then pair it with a wired smart thermostat fitted closer to the manifold. In this way when the wireless sensor calls for heat it forces its wired counterpart actually switches on the actuator.
- This means all the additional thermostats driven rooms will need two devices
- One in the room, a wireless sensor
- One at the manifold, a wired thermostat - linked through the app to its counterpart in the relevant room.
- You'll need to balance costs. There may be a limit on the number of thermostats that the X system can handle (the V systems have a limit of 25) - @Emcee would you provide input here please?
- This means all the additional thermostats driven rooms will need two devices
- Your photos dont present the pumps for the manifold. I presume each manifold has a dedicated pump, controlled by the manifold's dedicated wiring centre, which opens flow in the underfloor heating loop when the relevant room thermostat is intended to call for heat. A good underfloor wiring centre will enable you to lay it out well.
- Regarding what I call a motorised valve - this is one: Honeywell Home V4043B Motorised Zone Valve - 2 Port 28mm - 13974. They are usually fitted with 22mm joints and control the flow of heat to multiple manifolds.
- Regarding the heat pumps zoning. Have just talked to a friend who fits heat pumps. He said that a lot of calculation goes into planning a large house, when deciding on a configuration of a heat pump. He suggested you either talk to the company that fitted yours, or talk to the manufacturers, because of the calculations involved in choosing your configuration impacts the decision as to whether the motorised zone valves ever made sense.
- Given that you have underfloor heating and your heat pump are both operating with low temperature flows, there might be a value of zoning the first floor and second floor. Although the real work to assign heat flow is actually handled at the manifold underfloor heating actuators, if one floor is hardly used during the day, and at that time the other floor is busy, and this changes at night (I hope you see my point), then the motorised zone valves may make sense because you waste less heat in that scenario.
- Do check with the manufacturers first.
Is there anything more you need? Looks like you have a lot of wiring to do.
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@policywonk Thanks again! Actually the wiring is all there, apart from the 2 or 3 wireless thermostats I'd like to add. Since it's basically a brand new house (2022) and I don't want to break open any walls that have been neatly painted or wallpapered just 6 months ago, for the areas where there's no wiring, I would use the wireless versions. With those I can wire up the actuators to the white box and use the wireless thermostat in the room itself.
Such a Honeywell motorised zone valve is exactly what I had in my previous home and was placed just before the underfloor heating manifolds like you said. So it basically controlled the underfloor heating as a whole.
Regarding zoning: well to be honest, I also don't think I really need like 8 thermostats, but for two reasons I'd like to gain more control:
- Our house can generally be separated into three main areas: the first floor (living room, kitchen, hallway and such), the extension of the first floor (garage, bathroom, home office) and the second floor (bedrooms and bathroom). The past few days it's been quite cold here at around 0-5C, lots of rain, no sunshine, lots of wind and generally speaking terrible weather. I notice that when the living room and kitchen are heated up to 20,0C (to which it is set), the home office and bathroom over there don't get warmer than 18,0-18,5C. I've already maximised the flow to them by opening the flow meter valve to the maximum and I've set the wall thermostat to 25C (as it only acts as a shut off for that zone when that temp is reached), but still it doesn't get warmer. I know this also has to do with the fact that the underfloor heating pipes are laid out at 100mm separation in the living room/kitchen and 150mm in the hallway, garage, home office and bathroom. So even with identical flow going through them in terms of liters per minute, it will never get as warm as elsewhere. And since the Vaillant sensoComfort thermostat is placed in the living room, as soon as it reaches 20C there, it shuts off the whole heat pump, so it's impossible for me to continue heating the home office.
- Second reason is that the upper floor actually sometimes gets warmer than needed, we have a few Aqara temp sensors and a few Homepod Minis, both provide me with temp and humidity insights and sometimes it gets up to 19,5-20C upstairs while 19,0C would be just fine. We always stuck to 19,0C in our previous home (with Tado radiator thermostats) so a way to independently control the upper floor would also be nice.
Regarding the pumps: I see what you mean, I don't see a pump at the first floor either, could it be that this is purely controlled by the heat pump? Because my previous home did have a separate pump installed right by the underfloor heating zone/actuators.
I will check with the manufacturer and installer as well, see what they can tell me about this. Thanks so far for all your help!
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Brand new to Tado, so not an expert by any stretch. But reading this post reminded me of what I'd heard from Heat Geeks about the negative impact that zoning can have with heat pump efficiency. I'd recommend looking at their Youtube videos - very knowledgeable folks:
https://youtu.be/zpTVIeUh04E?si=wnzER_iTxan_1eOj0 -
Consider this:
- Turn up the thermal control at the manifold which looks after the area thats running cold.
- Dont forget that to get a Tado system to call for heat, all areas which need to call for heat must be on under Tado control. So you might want to consider using a Tado pair:
- One is a local wall smart sensor reading need in the room
- The other is the wired smart thermostat taking the reading and, through its wires opening the actuator.
Good luck. Come back if you need more help.
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