Testing Smart Homes

[Charlie_]

If done right then failsafes are put in place to prevent any issues.

TRV heads
“As a result there needs to be a by-pass valve”
Why is that then?

 

[Simon47]

Bypass requirement isn't changed by electronic TRV heads - wax heads can reduce flow rate so that a bypass is required.
Reason for bypass ? When TRVs throttle rads down there two issues.
First is having a fixed pump which will be pumping at higher pressure against the extra resistance. This results in a noisy system and in extreme can danage the pump. It can be simply solved by using a modulating pump like the Grundfoss Alpha range.
Second issue is that AFAIK there is not a single boiler on the market suitable for a modern system Resd the manual for any boiler and thay are all designed for fixed/minimum flow rates - and generally higher flow rates than most rad systems need anyway. So you need to keep the fixed pump, and install a bypass valve that will return hot water back to the boiler - usually stopping it condensing most of the time. An utterly terrible state of affairs with the boiler manufacturers (and government) seemingly oblivious to the stupidity of it all
It could be very simply solved with very minor changes to boiler plumbing - increasing efficiency and performance in one go. But then I suspect most "plumbers" wouldn't be able to understand it
Moi disparaging of plumbers and boiler manufacturers based on my observations

 

[EricMark]

I think we have to ask our selves what are we employed to do? If asked to look at the installation then we should not be looking at appliances, and a hand drier or immersion heater is an appliance.

The question arises what is the demarcation line.

I do see the point that be it wax or electronic the TRV can turn off the coolant, not a good example, but the question is, can the item either cause damage to person or equipment.

Maybe better example is a thermoplastic header tank. We all know about the baby death. But with a thermosetting header tank it would not have failed, why thermoplastic type is allowed I don't know?

However with a solid fuel water heater we have to use thermosetting or metallic header tank, and the over temperature device for the immersion heater needs to be the re-settable type, even without solid fuel the tank can go over temperature due to non electric heating so we want to be able to re-set the over temperature cut out. But with electric only water heating we want a non re-settable type, so if the thermostat becomes faulty, the whole thing needs renewing.

But nothing in my training to get my C&G2391 told me about reason or type of cut out fitted to an immersion heater thermostat, and why should they, this is an appliance, not part of the installation.

However C&G2377 Pat testing or inspection and testing of in-service electrical equipment to give full title, also did not tell me about matching the thermostat to the material used to make the header tank.

The same applies to a bench grinder over 370 watt, we know as tradesmen it needs a cut out so if there is a power failure it will not auto restart, but neither of the two, well three as there are two exams for PAT testing, told me to fail a grind wheel if it did not fail safe.

These points have been valid for many years, but today with "Smart" devices we have more items which need special knowledge of some type.

So if you have a 13A socket which can be remotely energised is this permitted? Well over 370 watt, I would say no, it does not comply, light switch rated 250 watt, so that does comply.

I know my wife's car has a warning that you should not remotely start it using your phone if it is on a public road, but in our drive she can start the car and let it warm up, so toasty warm when she gets in it, the gear selector knob does not rise when started with phone so no one can steel it, but as to if safe that's another question.

I am sure Jaguar has considered the safety aspect, but what about pofung or any other Chinese or other import? does it comply with British safety standards? Not a clue if there is some thing called pofung. But is it part of our remit to look for Chinese Export symbols i.e. CE marked?

I think it is time we just do our job, and not the jobs of allied trades, if we are doing an EICR the I stands for installation and that's all we should do, and we should state only the installation has been tested, and all electrical appliances be it fixed or portable are outside the remit and will not be tested as part of the EICR.

 

[Simon47]

Good roundup there.
But back to the original question, I think things are only going to get more "interesting"
For so long, we had a few RCDs (and other bits and pieces, but mostly RCDs) where the instructions were to disconnect them and do IR testing at 500V. With maybe one or two RCDs in a split board that's not too difficult to do - but a board full of RCBOs ? Now the model forms have a place to mark voltage used, and 250V is specifically allowed where 500V might damage equipment. Before this change, I was of the opinion that disconnecting to test at 500V was "not always a good idea" - think of the amount of disturbance in a CU when it's all RCBOs. In my rental flat, during periodic testing I found a high resistance neutral in the RFC - which I eventually tracked down to the connections in the RCBO. I'd specifically done testing at a socket as the RCBOs I used are not very easy to work with while the socket allows easy visual inspection of the connections when putting it back together. Had I done testing from the CU, I wouldn't have found the found, and it's quite possible I could have put it back together with the same (or another) fault. But as long as I use the old "press and hold the button, watch the needle" IR tester, I can test the IR of the whole installation in one go as long as I use 250V and one polarity (the RCBOs have a resistance to earth in the other polarity) - if the whole installation comes up with a reasonable IR, then every circuit in it must be OK on it's own.

For a household of "smart" stuff, as Brucie used to say, good game, good game I think you'd struggle to actually test anything other than the mains voltage stuff - and again this would probably have to be at 250V to avoid having to dismantle the whole installation. Then you have the problem of testing circuits that are switched by the smart stuff - so you can't test (eg) a light circuit all the way to the rose/pendant just by flicking the switch on the wall, and it might not be possible to switch it on via the "smart" gubbins while leaving it powered down for IR and Zs tests.
As for the ELV stuff, other than perhaps IR testing Class II devices to ensure that the ELV side is actually isolated from the supply, I see little you can actually do with them.

A little topical for me as I've recently been thinking of more work for myself at home - as if SWMBO doesn't complain enough about the jobs I haven't got done and those I haven't finished
I bought some scaffolding for doing those "stuff I don't like doing off ladders" jobs. Put it up to sort out the light on the back gable, and ended up using some conduit to change from one very high up PIR/floodlight to a PIR and two LED floodlights mounted less high up. Then I get to moving round the side to sort out the guttering, and remember that the light round there doesn't work. Then I start thinking that if I pick up a feed from the cable that feeds that, I can change the switch in the living room to override PIR on the back instead of switching the feed. And then while I'm doing that, realise that if I use a tee box instead of a bend, I can drill through the wall and end up in the boiler cupboard which opens up all sorts of possibilities. So now I;ve gone from "fix the light" to a conduit run across the gable, round the side, along under the eaves, and into the boiler cupboard - with tee boxes for the two PIRs and three lights
Then I started thinking about more fancy lighting and whiel browsing for RGBW lights, came across a manufacturer offering what they call "series" lighting which is basically the RGBW LED mitter with no drivers. So now I'm thinking that at a future time, I'll pull out the 240V wiring, pull in some ELV wiring (remember, got all the conduit in place now), rip some fittings apart and replace the innards with some bare LumiLED RGBW emitters - and I can fit DALI controlled 350mA or 700mA drivers in the boiler cupboard and have mood lighting in the garden
Bet SWMBO won't be impressed though - that's the major limitation for stuff I do, the WAF which isn't always positive

 

[EricMark]

I no longer work, but seem to remember BS requires items will not be damaged with 500 volt IR testing, so if damaged it is likely sub-standard anyway, but no real harm using 250 volt, but you have to remember 230 volt RMS is around 325 volt peak so really 250 volt is not high enough. 500 volt is only 140 volt more than standard peak voltage for 254 volt RMS. And not testing line to neutral so in real terms only the capacitors on supply filters likely to be damaged.

The best practice guide tells us to fail having too many extensions hanging off a socket, but as long as we affix a sticker, and Class II used we can allow no earth on lights. But the earth rule was changed in 1966, at one time we could use knife switches, so just because years ago we could do it, does not really mean OK today, and BS7671 has never allowed lights without earths, it was not BS7671 until 1992 so was never permitted on a previous edition.

But at the end of the day, aim is should it all go wrong, you can point to some one else to blame.

On the negotiations to buy this house, I was provided with an electrical installation certificate which showed half the circuits through a RCD and all circuits MCB protected, the reading were slightly suspect where PFC and loop impedance didn't seem to follow ohms law, but it was a reasonable document. On taking possession I wanted to do some electrical work, and found turning off main isolator had no effect what so ever on the electrical supply to house. On inspection found an old Wilex fuse box hidden in the ceiling.

The central heating was supplied from three separate FCU's and two separate distribution boxes one a fuse box, the other a consumer unit, the programmer although it said CH and DHW in fact was a simple time switch to boiler supply, and switching between CH and DHW and DHW only had no effect. The central heating pump for main house was simply on a 13A plug. There was a thermostat for the flat below main house, and there was a RF receiver for a wireless thermostat, but no actual wireless thermostat connected to it.

I came to trace wires, from where one would expect the main house thermostat to location of time switch found 3 core and earth red, yellow, blue, from the time switch also 3 core and earth red, yellow, blue, but in flat the three core and earth was brown, black, grey and there was only continuity in two of the three wires.

The floor under the cistern was bowed to the extent wondered if cistern would arrive on ground floor over night, and the floor in other areas was also damaged, and under the shower it needed the main beam renewing. But house buyers report did pick up minor leak on flashing around chimney, plus signs of water around patio door, but missed the rest.

As to any claim not sure, but I suspect not, and this is the problem, in the main, the house buyer report, or EICR, or energy rating, is just some ones opinion and unless some one is killed, unlikely to end up as a court case.

So why do we bother?

 

[PEG]

I remember a project of 5 new-build "smart homes",with a right arrogant pair of nouveau cool developers...

One was up to DPC,with temp electric,water,and gas,drains to connect.

I spent a few hours,checking the layout,and had spotted a few issues,and had questions to ask. The pair had a problem with my asks,and responses varied from "not your problem" to "i think others will have considered that...."

One my questions,i decided to keep to my self....it concerned the fact that on the drawings,it had a direct connection to the combined waste,pavement side,but a quick lid lift,showed the invert at that position to be 300mm higher than the properties....oops...

They were going to need either a house jack....or a non-specified pumping station....

The other 4 are now built,the original pair having gone bump,and they are 1M higher than the first

My point is that you can aspire to the most smart,eco friendly hi-tech house in the world,but the obsession with these ideals,can sometimes take ones eye off the fundamentals ...and gravity is better for the planet than two pumps cycling day and night...

 

[EricMark]

To cure a problem with the sun on bay windows causing room temperature to shoot up, but radiators were still hot, I fitted some electronic heads on the TRV's.

Since these had the option for geofencing I thought why not, however they were too clever for their own good, they have anti-hysteresis software, and this means at 12 degs and set to 20 degs first 6 degs is fast, but last 2 degs it takes hour and a half designed to stop it over shooting.

However in coolest days, temperature would rarely drop more than 3 degs in 8 hours, so unless you worked 2 hours from home it was rather pointless.

Also idea was rooms can be set to different temperatures, however insulation to outside was very good, but room to room rather poor, so even with one bedroom switched totally off, it was only 2 degs cooler than other rooms.

The electronic valves were faster acting to over temperature and they reduced the spike by 4 degs, however having a TRV set to deg C rather than * to 6 one was aware when it allowed the room to over heat, and it was found the setting of lock shield valve could be critical, however it was not the same with all radiators, then realised why, with TRV on supply the sensor heats up quickly, but if on return whole radiator can get hot before the sensor gets any heat.

It is all well and good saying the valve is bi-directional but unless fitted on supply side, they over shoot rather easy.

So it was found the main advantage of the electronic head was not wifi, or geofencing but having the temperature displayed in degs C, so one knows if the lock shield valve needs opening or closing to get the temperature set same as actual temperature, with TRV on return by turning down the lock shield valve the radiators heats up more gradually so the TRV has time to act.

So in most rooms setting lock shield so electronic head gets correct temperature then swapping back to wax, and the wax worked nearly as well as the electronic.

But even a simple wireless thermostat instead of hard wired can cause health and safety issues, when living with Mother I would realise when some thing had gone wrong, but when we only visited I had changed the Honeywell wireless thermostat for a Horstmann programmable wireless thermostat so at night the house would not get too cold, with Mother living down stairs the ground floor rooms get a lot colder over night.

However I visited to find room at 28 degs C, it seems the Honeywell had a fail safe, if no signal in 30 minutes it switched off, however that was not case with Horstmann, happened a few times, placed in a draw, to flat batteries result was same, and 28 degs C far to hot for a 90 year old.

I am sure Horstmann do make better models, but looking on the sales info neither say about fail safe, you have to read deep into the instructions.

Be it closing a window, or heating a room, as the installer we need to consider health and safety, with a Velox window in the roof it is unlikely any one will get their fingers in the works for a blind closer, but the same device on a patio door, and it could injure a child.

But do we have the skill required? We can't know everything, once pointed out is seems simple common sense, but until pointed out you do not see the problem.

An example is disabled parking bays, just look how many have a post in the centre so car rear door can't be opened and ramp dropped, so people have to be unloaded and loaded into the traffic, unless you are involved with some one in a wheel chair, you simply don't see the problem.

Be it a security gate, or window blind, we simply don't have the training to identify danger, and that raises the question should be even try? If it complies with electrical regulations, should we worry about the others? Clearly in some cases yes, location of sockets for use by disabled for example, but again as installer yes, as part of an EICR should we say when a socket it too near to corner of a room, too high, or too low?

 

[Simon47]

... it was not the same with all radiators, then realised why, with TRV on supply the sensor heats up quickly, but if on return whole radiator can get hot before the sensor gets any heat.

It is all well and good saying the valve is bi-directional but unless fitted on supply side, they over shoot rather easy.

Actually, the sensor getting heat from the pipework is a "fault". It should only be sensing the air temp - and in that respect, an electronic head can (depending on the software) react much more quickly since the wax device needs time and temperature difference to absorb/lose heat.
That is why it is recommended that TRVs are on the return, and the heads are horizontal so as to be away from radiant heat from the rad and warm convection from the pipe.

The way you've described it with the TRV on the supply so it's affected by heat from the pipe, it means the TRV always operating with an offset since the pipe will (nominally) always be the same temp other than when the TRV is completely closed.
So when the room reaches temp and the TRV closes off, the pipe will cool, the TRV head will cool a bit - and so open slightly and leave the rad slightly warm.
A TRV can't work magic, it's important that the system is balanced - the combination of flow temp, flow rate (lockshield setting), rad size needs to be appropriate to the room. As you've found, if the lockshield is too open, then the rad can fill quickly with more hot water than is needed for the heat demands of the room.

But at the end of the day, it's a control loop. Without careful tuning (and a PID control function) then it's going to struggle - especially when subjected to a step change in setpoint.

This will be why your electronic heads have this "slow down as we approach the setpoint" feature. It gives a quick resonse to a large error, but slows things down where it matters. It's the ONLY way to make a generic electronic TRV that will "just work" for the majority of users - few users could cope with PID tuning..

 

[EricMark]

Actually, the sensor getting heat from the pipework is a "fault". It should only be sensing the air temp.

The eTRV has two sensors, one for air and one for water, the water one compensates the air one for the heat it gets direct from the radiator, this is part of the design, not a fault. At least for the MiHome Energenie I have fitted.

But there is a limit to how fast it can open or close,

After 5 seconds the motor will start up to exercise the valve stem. You may need to wait several minutes for this process to complete.

this is from the instructions to fit batteries, and if as clearly can happen the boiler is not running, the valve can open over the required amount, when boiler starts and it detects the heat, it starts to close, so flow is modulated rather than simply switched off/on.

However if fitted on the return it starts to modulate slower than on feed, I know as I have used them both on feed and return, so when fitted on feed clearly the lock shield valve still requires trimming, but it is no where near as critical as when fitted on the return.

 

[Simon47]

The eTRV has two sensors, one for air and one for water, the water one compensates the air one for the heat it gets direct from the radiator, this is part of the design, not a fault. At least for the MiHome Energenie I have fitted.

That's specific to the brand of eTRVs you have. It doesn't apply to all eTRVs, and AFAIK it doesn't apply at all to any non-electronic TRV heads. It does demonstrate that you need to understand the specifics of whatever you are installing/using.

 

[EricMark]

I note the cheaper TRV £10 or £15 with bluetooth eqiva has an offset temperature to allow for the heat from the radiator, +/- 3.5 degrees C max, mainly I think for when multiple valves fitted in one room.

With electronic heads down to £10 one wonders why people still use the old wax type, I suppose don't want to change batteries?

However it means paying £40 for a head, £30 is just so you can adjust it remotely, so is it really worth £30 to adjust from your phone when away from home?

OK there are other advantages, the Hive TRV states "If you also have a Hive thermostat you can enable Heat On Demand to automatically boost your heating when a radiator needs heat." it also says "Note: Hive Hub 1 does not support Hive Radiator Valves." but be it Tado, EvoHome, Hive or Nest much depends on how far you going with the installation, boiler type, and local wiring which will work within a reasonable price.

But how does one compare the options, take Hive and Nest as an example, Hive wall thermostat is cheaper than Nest, but the TRV's are much more expensive, and Nest will work with OpenTherm, Hive will not, but Nest the TRV simply follows the wall thermostat where Hive TRV switches on the boiler through the thermostat. Nest both Gen 3 and e are volt free, Hive only single channel is volt free, so both have plus and minus features which take a lot of reading to find out.

I like the ability to connect Nest thermostat to heat link hard wired so not relying on wireless link, but it often depends what wiring is already installed.

But back to question, how do you test? Or even should it be tested? Well the Nest heat link instructions say the earth is only required when the thermostat is hard wired, so I read that as earth is required when hard wired thermostat is used.

At the heat link easy to test the earth, but at the wall thermostat, first problem is how do you gain access, I know the round lump simply pulls off, but unless you have fitted one, you would be a brave man just to tug. Then you need to find another earth to test it to.

So the box of adaptors gets larger and larger, where do you stop? This house I had to dig out the living room ceiling rose to change it, OK to change it, but just to test? It now has a Maestro plug in ceiling rose, so all you need to do is unplug the chandelier, and plug in your test adaptor, if you have one, otherwise you have to remove plug from chandelier, now a Hager Klik ceiling rose is only £4 so a spare plug for them OK, but the Maestro is £23 having one of them in tool kit is unlikely.

And how many instruction manuals are you going to read? As said Nest is class II unless thermostat hard wired, so what about the rest, just because there is an earth terminal does not mean it has to be earthed.

When I did my C&G 2391 all those years ago, it took me around an hour to test the board used for the test, at that rate it would take a day even for the simplest of house. To just test one ceiling rose earth one needs a set of steps, and if using an electronic switch getting power not easy.

If I said to test a house it will take 12 hours at £15 an hour I don't think I would get much work?

So big question, is the boiler, thermostat, programmer etc part of the installation, or is it an appliance? Does it come within the remit of doing an electrical installation condition report? Supply to boiler yes, everything supplied from the boiler, not so sure.