Homebrew zone valves

[Radian]

I have a pathological hatred of typical 2-port valves. They all seem to be based on the same ancient, crappy, design of a synchronous AC motor that gets hot when driven to stall, via a micro-switch hacked-in current limiting resistor (that also gets hot) dissipating something in the order of 6 Watts. Getting on a bit in years, I've lost count of the number of actuator heads I've had to replace and the price of them was beginning to feel more like a tax on owning a heating system.

 

The final straw came on a frosty X-mas morning when the heating didn't come on because...

 

That was a couple of years ago and because SFix & TSn were closed for the festivities, I enlisted a Raspberry Pi, stepper motor and 3D printer to be hero just for one day. This episode gave me a taste for getting back control of my heating system and I have not looked back since.

 

These days I use a bunch of drayton 2-port valve bodies (£3 Ebay) with a micro metal gearbox motors (<£5) driven by Pololu H-bridge constant current drivers (£5) mounted on some scrap metal:

 

 

My question is... do people around here just put up with the typical Honeywell/Drayton valves circa £60 or do they go for something more exotic (that I've yet to find) or are they rolling their own like me?

[Kelvin]

Interesting. I hate the feckers too. I’ve just replaced two of useless things at a cost of £100. Worse than that the tails were shorter than the same model I took off so had to bugger about sorting that as well. They have failed in every house I’ve owned. 

Edited December 5, 2021 by Kelvin

[ProDave]

I actually find the Honeywell ones quite reliable.  Agree the Drayton ones are pants.

 

If you think 2 port valves are bad, you have obviously never had a system with a 3 port mid position valve.

[Radian]

14 hours ago, Kelvin said:

Interesting. I hate the feckers too. I’ve just replaced two of useless things at a cost of £100. Worse than that the tails were shorter than the same model I took off so had to bugger about sorting that as well. They have failed in every house I’ve owned. 

 

Regular failures are a sign of poorly engineered products. But what about the power consumption? I don't see any discussions about this but 6Watts 24/7 x how may valves are in play? Some people can heat their whole PH on that!

 

13 hours ago, ProDave said:

I actually find the Honeywell ones quite reliable.  Agree the Drayton ones are pants.

 

If you think 2 port valves are bad, you have obviously never had a system with a 3 port mid position valve.

 

I thought that about Honeywells too, to begin with, but that was the last type I had to replace. And yes, the 3 port mid - I had one that went both ways irrespective of where the shaft was pointing. At least the actuator wasn't to blame in that particular case! I took it apart expecting to see a missing rubber seal but it all looked kind of OK.

[epsilonGreedy]

4 minutes ago, Radian said:

Regular failures are a sign of poorly engineered products. But what about the power consumption? I don't see any discussions about this but 6Watts 24/7 x how may valves are in play?

 

 

Following the latest kWH price hikes I think each phantom Watt-Year now costs £1.70.

 

Your DIY valve port interests me because I would like per room zoned heating but I also dislike the thought of building a new house that is dependent on wifi at each radiator for heating automation.

 

Currently mulling over the idea of computer controlled values mounted at a central heating distribution manifold with dumb (wax) TVRs on each radiator to control room temp.

 

The dream setup would allow "Alex, heat bathroom for 8pm", even better would be a locally hosted open source Alex but such initiatives seem to be struggling.

[PeterW]

29 minutes ago, epsilonGreedy said:

Currently mulling over the idea of computer controlled values mounted at a central heating distribution manifold with dumb (wax) TVRs on each radiator to control room temp.

So why not use the standard UFH manifold and the Wunda automatic balancing valves ..? They just need a 230v supply and they balance to delta 7°C difference and are about £20 each. Then a cheap thermostat in the room - wired or wireless , and you can flow to a zone or even individual rads. 

[Radian]

10 minutes ago, epsilonGreedy said:

Your DIY valve port interests me because I would like per room zoned heating but I also dislike the thought of building a new house that is dependent on wifi at each radiator for heating automation.

If you do go down that route, a £30ish Zigbee TRV could be your best bet. There's a zigbee2mqtt project that can be run on Raspberry Pi which, with the addition of node red could let you knock-up your dream-come-true entirely self-hosted setup.

 

I have a blend of both approaches to zoning but when you can home-brew a  motorised valve for well under £20 zoning each room does seem attractive.

 

 The motors I've used can also be fitted with a hall-effect sensor that encodes shaft position to give full servo control to make proportional valve opening possible. I haven't done that because I only needed three zones that all have their own temperature controlling components.  I do make use of the fact that the motor's braking isn't quite up to holding the valves fully shut... to pinch them off I keep the motors in stall (the constant current driver does this loss-lessly through PWM) but when my tiny UFH zone is the only load, the boiler can't modulate down low enough without cycling so I keep the main radiator zone slightly open which has the effect of gently pre-heating them in the wee small hours.

[Radian]

10 minutes ago, PeterW said:

So why not use the standard UFH manifold and the Wunda automatic balancing valves ..?

Yes, manifold distribution would be the way to go for more than a couple of zones and those are designed with an eye on power consumption at least. How long are the sensor leads out of curiosity?

[PeterW]

From memory they are about 250mm

[joth]

1 hour ago, PeterW said:

So why not use the standard UFH manifold and the Wunda automatic balancing valves ..? They just need a 230v supply and they balance to delta 7°C difference and are about £20 each. Then a cheap thermostat in the room - wired or wireless , and you can flow to a zone or even individual rads. 

(Nit: The auto balancing valves are by Salus, not Wunda, although obviously that's one place you can get them).

 

I was wondering about this very idea this morning. I'm considering getting 2 more fan coils (FCU) for the loft, to have one per bedroom. I was debating between a pump per FCU (ouch and yuck), and zone valve per FCU (ouch), or just branching to all three and simply not running the air valve when a given room is not calling for cooling (slightly yuck).

But then I thought why not add a manifold in the loft, with actuator per room. (perhaps chained to the air fan for each room). Does that sound sensible? It'd make a very nice isolation point too, if maintenance is needed on a FCU without having to drain down the system.

 

I don't think I'd want self-balancing actuator, as a FCU will work much better with substantially more than a >7ºC drop I'm sure.  

 

 

[epsilonGreedy]

1 hour ago, Radian said:

If you do go down that route, a £30ish Zigbee TRV could be your best bet. There's a zigbee2mqtt project that can be run on Raspberry Pi which, with the addition of node red could let you knock-up your dream-come-true entirely self-hosted setup.

 

 

I am only part way through my learning curve on Home Automation. I understand that Zigbee is a wifi home automation standard that runs on a wifi mesh topology.

 

I would not be happy moving into my new house and imagining the electromagnetic spectrum fizzing with a plethora of HA gadgets chatting 24/7 via wifi. My hope to get my limited HA plans implemented via wired controls or POE. The most popular HA projects don't appeal to me, I just want fine grained control of heating, detailed consumption stats at the 5 to 10 most power hungry sockets in the house, a robot vacuum and a sunrise smart light in the bedroom.

 

Re. the heating. I want zoned controls of the following. UFH zone x 2, 3 rads upstairs and 2 rads downstairs. Happy to go with a standard manifold but the details of a wired link from a HA server to manifold zone valves evades me so far.

 

I think @PeterWis hinting that a classic installation time only flow balancing could be thrown out of kilter with a highly zoned system. I will look into his auto balancer suggestion. 

[epsilonGreedy]

1 hour ago, PeterW said:

So why not use the standard UFH manifold and the Wunda automatic balancing valves ..? They just need a 230v supply and they balance to delta 7°C difference and are about £20 each. Then a cheap thermostat in the room - wired or wireless , and you can flow to a zone or even individual rads. 

 

 

So these valves also include a signal input wire that will allow a home automation server to open the flow to a UFH zone or an individual rad?

[Radian]

13 minutes ago, epsilonGreedy said:

Re. the heating. I want zoned controls of the following. UFH zone x 2, 3 rads upstairs and 2 rads downstairs. Happy to go with a standard manifold but the details of a wired link from a HA server to manifold zone valves evades me so far.

 

One of the many relay boards like these on the market (make sure it has opto-coupled inputs) could be wired to the GPIO pins on a Raspberry Pi and power 240V valves like the Honeywells or Wundas. Theres even a POE hat to power the Pi. Tons of HA software already available or you can piece together your own in node red.

 

You do seem to have a thing about EM though... I hope you appreciate that the power levels of deliberate radio sources like routers and wifi gadgets are incredibly tiny compared with cellphones, radio base-stations and even accidental sources like - oh, just about anything with digital electronics! That's why the range is always so pathetic by comparison.

[epsilonGreedy]

14 minutes ago, Radian said:

One of the many relay boards like these on the market (make sure it has opto-coupled inputs) could be wired to the GPIO pins on a Raspberry Pi and power 240V valves like the Honeywells or Wundas. Theres even a POE hat to power the Pi. Tons of HA software already available or you can piece together your own in node red.

 

 

Thanks. I had not appreciated that the intermediate circuitry to do mains power switching is so cheap.

 

Has anyone estimated the power consumption of a Pi across a whole year when performing a micro controller type task? I had been looking at an Arduino that can be put into a very power efficient sleep mode.

 

I see node-red getting mentioned in the HA world. I would prefer to program in C# but IOT and .Net is very niche. I hope node red can be programmed in TypeScript because I loath JavaScript.

[Radian]

NR is built on JS so no luck there. How bad is it though? Pi is generally a Watt or two. The actual difference between this and Arduino powered from a USB charger would be negligible. If you were really keen, you could easily do a PV/battery UPS to run it off-grid.

[joth]

I'm also disinclined to have core building service like heating be driven by Wifi or other wireless protocols, mostly for a stability and maintainability reasons rather than fear of EM waves.  Pi is OK for some tasks but I find them rather heavyweight for simple device control, and another thing I have to "keep up to date".

For this sort of use case my preference would be an ESP32 with PoE support e.g. https://www.olimex.com/Products/IoT/ESP32/ESP32-POE/open-source-hardware

This has 16 GPIOs so could easily drive a couple of those relay boards linked by Radian. And other than an ethernet drop, no more power or data connections required. Annual power consumption would be virtually nil.

 

My personal preference is using ESPhome to configure and drive them, but loads of other options available.  I have a Pi running emonpi for energy monitoring, the damn thing has 2 wall warts wifi and ethernet but falls over every few months, but the ESP devices I have are virtually zero maintenance (and when I need to do anything, it's all via the Home Assistant web UI). Each to their own   but I do like this setup.

 

[epsilonGreedy]

14 minutes ago, Radian said:

NR is built on JS so no luck there. How bad is it though?

 

 

TypeScript compiles down to JavaScript so in theory it could be used for Node-Red. In practical terms doing this really comes down to having a community of developers creating interface libraries to present core Node-Red concepts as TypeScript interfaces. There seems to be some related activity:

 

https://www.technicalfeeder.com/2021/07/how-to-implement-node-red-node-in-typescript/

 

Over in the non IOT world of software development many large teams have switched over to TypeScript.

 

20 minutes ago, Radian said:

Pi is generally a Watt or two. The actual difference between this and Arduino powered from a USB charger would be negligible. If you were really keen, you could easily do a PV/battery UPS to run it off-grid.

 

 

My motivation is not about being offgrid but I am concerned that a run-away of adoption of HA technology could start raising the household phantom watt count to the point where it might negate the savings from a high-tech heating control system. 

[Radian]

1 hour ago, joth said:

Pi is OK for some tasks but I find them rather heavyweight for simple device control, and another thing I have to "keep up to date".

Sure. The only reason I used mine in this role was to host an mqtt server and sql database. I've got plenty of ESP8266s and ESP32s pushing/pulling stuff into those.

Can't beat bare metal STM32 or even a PIC chip for a bit of PWM over a myriad of IO's ?

[epsilonGreedy]

49 minutes ago, joth said:

I'm also disinclined to have core building service like heating be driven by Wifi or other wireless protocols, mostly for a stability and maintainability reasons rather than fear of EM waves.  Pi is OK for some tasks but I find them rather heavyweight for simple device control, and another thing I have to "keep up to date".

For this sort of use case my preference would be an ESP32 with PoE support e.g. https://www.olimex.com/Products/IoT/ESP32/ESP32-POE/open-source-hardware

 

 

Before your post my thinking had gravitated towards an ESP32 solution. One microcontroller could control the manifold actuators and then if the ESP32 could talk MQTT across the house LAN I could skip to whole confused landscape of Home Automation and control the heating system n C# code running on a .net server. Once on my home turf of enterprise programming it would not be a major effort to knockup a mobile app to control the heating zones on-demand as a rough and ready equivalent of the Drayton/Wiser mobile heating app.

[SimonD]

23 hours ago, epsilonGreedy said:

Re. the heating. I want zoned controls of the following. UFH zone x 2, 3 rads upstairs and 2 rads downstairs. Happy to go with a standard manifold but the details of a wired link from a HA server to manifold zone valves evades me so far.

 

Before you go too far on the zoning, it might be worth considering what these guys have to say about it although it obviously doesn't work like they say for all situations.

 

[epsilonGreedy]

47 minutes ago, SimonD said:

 

Before you go too far on the zoning, it might be worth considering what these guys have to say about it although it obviously doesn't work like they say for all situations.

 

 

Thanks for that, I encountered this YouTube channel when viewing their riposte to the Skillbuilder anti heat pump video. Despite initial impressions they are a pair of smart dudes worth listening to.

 

They raise some important points that I should consider but I am not sure if their general advice is applicable in my case:

1. My house has an L-shape and I intend to zone the heating across a natural boundary at the L intersection.
2. When calculating internal heat transfer between heated and unheated rooms they assume a U-value of 2W per m2 per Kelvin across internal walls. I expect that a modern internal stud wall with sound insulation wool will be better than that.
3. I hope unheated rooms will drop lower than 18 degrees when it is -3 degrees outside thus lowering the overall building loss.

Over all their video does highlight that with an ASHP the total heating costs might rise when zoning is used in an attempt to lower energy bills.

 

I was surprised to hear that gas boiler efficiency also drops significantly when the circulation temp rises to compensate for the loss of emitters in the cold zones. 

[joth]

Interesting video. Makes it even stranger that part L2A (section 2.43) is pushing for more zoning and finer control in modern installs.

 

[SimonD]

20 hours ago, epsilonGreedy said:

Despite initial impressions they are a pair of smart dudes worth listening to.

 

I saw that video too and like the Skillbuilder heatpump rant, I skipped most of it. But this one did contain more sense ?

 

20 hours ago, epsilonGreedy said:

Over all their video does highlight that with an ASHP the total heating costs might rise when zoning is used in an attempt to lower energy bills

 

19 hours ago, joth said:

Interesting video. Makes it even stranger that part L2A (section 2.43) is pushing for more zoning and finer control in modern installs.

 

Having reflected on the video, I came to the conclusion that it probably just points to correct design of the system at the outset as the main problem occurs if you design the heat emitters for uniform output throughout the house. My vague recollection is that the CIBSE standard heat loss method recommends different temperatures in different rooms (e.g. bathroom and kitchen, although it doesn't account for heat loss/gain between internal spaces.

 

I'm sure the problems they highlight can be overcome by modifying the heatloss calcs and heat emitters accordingly and also if necessary include a buffer within the heatpump circuit to reduce cycling?

[epsilonGreedy]

16 minutes ago, SimonD said:

I'm sure the problems they highlight can be overcome by modifying the heatloss calcs and heat emitters accordingly and also if necessary include a buffer within the heatpump circuit to reduce cycling?

 

 

I thought the requirement for a buffer tank was specific to ASHP+ UFH but I am starting to wonder if a highly zoned heating design with a gas boiler, needs one as well. Right now I have crossed back to gas central heating camp having settled on an ASHP for the past 6 months.

Edited December 8, 2021 by epsilonGreedy

[SimonD]

1 hour ago, epsilonGreedy said:

 

I thought the requirement for a buffer tank was specific to ASHP+ UFH but I am starting to wonder if a highly zoned heating design with a gas boiler, needs one as well. Right now I have crossed back to gas central heating camp having settled on an ASHP for the past 6 months.

 

I think that may very well be the case if your last open heat emitter can't radiate sufficient heat and your boiler can't modulate down far enough. Anscillary to this discussion I think a major problem lies in how we combine heating and hot water. For example, looking at gas boilers for my current build (we've run out of budget for Air to Water HP right now), if I'm to size output for reasonably fast DHW recharge, then the boiler struggles to modulate down its CH output low enough for normal house heat demand. For example, I have a calculated load of 5.8kW calculated at the standard -3/21 with half the house at -3/18. A Baxi 18 or 24kW system boiler can only modulate down to 4.9kW at 50/30 or 4.5 at 80/60. It's better with an Ideal Vogue as I could go 15kW boiler modulating down to 3.0kW. But for some of the year, it's likely going to be cycling more often than I'd like.

 

At the moment, I'm sorely tempted to look at separating the CH and DHW systems in some way. E.g. a gas water heater and air-to-air heatpump, but that may have to wait a few years until budget allows.