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Heatmiser Neostat v2 temperature sensor problem


Ultima357

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4 minutes ago, Onoff said:

 

If you can CAD up a model and provide an stl file one of us can print a prototype.

Thanks for the offer. I'll have a look at what is around, if not I'll knock one up in Sketchup and see what can be done. Trouble is I need 11! (3 are already remote in bathrooms) You can get the ones same size as single gang outlet but they are not too pretty! 

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Having looked around, I found some quite neat small enclosures, but instead of adding lumps on the walls, I did a little more probing and found at about 10mm below the unit, the heat it generates is not in play. So ordered some miniature thermistors on 75mm wire tails that I can hook into the remote air sense terminals and just poke them out of the bottom edge. Unobtrusive, safe enough and cheap at £1 each. Guess I could even dab a spot of wall colour paint on them to disguise them some more. Will pester Heatmiser though to do V3 with fully vented enclosure. 

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23 hours ago, Ultima357 said:

Thanks for the offer. I'll have a look at what is around, if not I'll knock one up in Sketchup and see what can be done. Trouble is I need 11! (3 are already remote in bathrooms) You can get the ones same size as single gang outlet but they are not too pretty! 

 

Printing 11 isn't a massive deal tbh and wouldn't use much material. What I find for things like this is (to my mind anyway) the quality is lacking. The models I create look a million bucks:

 

Makita-Rolson_004

 

The reality can be a bit "grainy". One of my models brought to life by my lad:

 

20200422_102521

 

Saying that, what some people will print and be happy with is dog rough appalling imo! NOT one of mine btw:

 

rough

 

Have had some success plastic priming and spray painting parts. 

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5 hours ago, JFDIY said:

What about making a spacer plate to sandwich behind the stat and protrude below enough to house the sensor.

 

Could make from acetal or white perspex sheet and polish the edges to look decent.

Unfortunately in these stats, the face plate plugs into the backplate which houses the psu and 230vac terminals via a multipin connector moulded into the faceplate. Faceplate male, backplate female. Additionally it clips at the top and fastens via small screw at bottom. I did try easing it forward to see how that affected the internal temperature but it just isn't possible. Had iit been possible, it would have been a nice way to improve matters with a vented spacer. 

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1 minute ago, Ultima357 said:

Unfortunately in these stats, the face plate plugs into the backplate which houses the psu and 230vac terminals via a multipin connector moulded into the faceplate. Faceplate male, backplate female. Additionally it clips at the top and fastens via small screw at bottom. I did try easing it forward to see how that affected the internal temperature but it just isn't possible. Had iit been possible, it would have been a nice way to improve matters with a vented spacer. 

 

Can't figure a female to male extender for the connector?

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3 hours ago, Onoff said:

 

Printing 11 isn't a massive deal tbh and wouldn't use much material. What I find for things like this is (to my mind anyway) the quality is lacking. The models I create look a million bucks:

 

Thanks for the offer. I'll have a trial with the remote ones, see what results I get. If they work well, it might be possible to make a small bubble to hide these. 

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8 minutes ago, Onoff said:

 

Can't figure a female to male extender for the connector?

No, the clip/screw arrangements are not compatible with bringing it forward. Pics show details hopefully. This one that I've experimented with remote sensor left over from heating installation. It only engages the terminals just as it clips back, so engaging the pins by 2mm max. All a bit fine detail to make a reliable/neat spacer I think? The wire is the remote sensor not there in normal install. 

    

16112674292552828522001580880036.jpg

16112674644292996129736424102788.jpg

Edited by Ultima357
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Looking at my photos just got me thinking. Maybe a standard surface box, back removed, vented with neat holes installed between the back plate and wall using longer screws might vent the heat enough to stop the self heating? Tomorrows project maybe... 

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5 minutes ago, MJNewton said:

Do I recall you saying the self-heating was suspected being down to the internal PSU? If so, could you remove that and just power it via low voltage from a remote supply? 

Unfortunately not. It switches the mains to trigger the uhf actuators via wiring centre. 

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Wiring diagram below. This might help everyone understand how it's wired. Left hand diagram shows the wiring to Heatmiser wiring centre which operates the UHF actuators, turns on the pump and calls the ASHP into action. The 230vac circle indicates the psu for the stat faceplate. 

16112685590522578669934618448579.jpg

Edited by Ultima357
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20 minutes ago, Ultima357 said:

Looking at my photos just got me thinking. Maybe a standard surface box, back removed, vented with neat holes installed between the back plate and wall using longer screws might vent the heat enough to stop the self heating? Tomorrows project maybe... 

 

Might be some ideas on Thingiverse?

 

https://www.thingiverse.com/thing:3914359

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8 minutes ago, MJNewton said:

That doesn't necessarily rule out powering it via low voltage if the volt-free relay is powered from the low voltage side of the PSU.

Hmmm, don't know is the answer. The relay is all part of the moulded lump behind the backplate not shown in my pictures, so you'd have to remote the whole bit, meaning an 8 way low voltage wiring. All gets a bit messy considering I have 11 of the 14 to do. Think I'm going to try the standard surface back box idea as well as the remote thermistors which I've already ordered. The remote thermistor I've already experimented with works, just need to make it pretty. I also found out today, chasing the interference fairies caused by the central vacuum system (which I think I mentioned in the first post) , that the remote thermistor overcame this issue too. This is a very weird one caused by the 12v switch line of the central vac. Tried decoupling capacitors on it today to no effect. Run the vac, and the stats show a gradually increasing temperature which continues to rise 0.1 to 0.2 deg after vac is turned off before drifting back down to normal. It's like the interference causes the thermistor to heat up.... As I said, it's a weird one. 

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14 minutes ago, Onoff said:

 

Might be some ideas on Thingiverse?

 

https://www.thingiverse.com/thing:3914359

Yes, they look like the business. Just need ventilation holes all round the edge and in white plastic. I'll get to butchering a standard one first to see if it works out, they're only about a quid. But that said, see my post above about the remote thermistor also curing my interference problem. Might be a combination of these two ideas that wins the day. 

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14 minutes ago, Ultima357 said:

Hmmm, don't know is the answer. The relay is all part of the moulded lump behind the backplate not shown in my pictures, so you'd have to remote the whole bit, meaning an 8 way low voltage wiring. All gets a bit messy considering I have 11 of the 14 to do.

 

Understood, and agreed, and I'm only thinking out loud (and not considering the inevitable differences the difference between how doable something is in theory vs practice!). 

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1 hour ago, Ultima357 said:

No, the clip/screw arrangements are not compatible with bringing it forward. Pics show details hopefully. This one that I've experimented with remote sensor left over from heating installation. It only engages the terminals just as it clips back, so engaging the pins by 2mm max. All a bit fine detail to make a reliable/neat spacer I think? The wire is the remote sensor not there in normal install. 

    

16112674292552828522001580880036.jpg

16112674644292996129736424102788.jpg

 

 

Have you considered smashing a load of holes in the white backplate, then spacing that off the wall (if needed) to get airflow

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54 minutes ago, PeterW said:

 Isn’t that one of the things I posted and I’d do them top bottom so you get airflow ... 

 

Sorry, missed you saying/sketching that. Could even put the slots on a slight slant... top, bottom, side, wherever.

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9 hours ago, PeterW said:

How about one of these with slots cut in the top and bottom edges to allow air to flow ..? Isn’t the transformer in the back box behind that octagonal plate ..?

Yep, that's a good one. You are correct, the transforrmer/psu and relay are in the back box behind the octagonal plate. You just ease the screws, rotate slightly and it all comes forward. Undoubtedly the source of the heat as I've measured the face of the octagonal bit at 29deg.

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16 minutes ago, Onoff said:

 

Sorry, missed you saying/sketching that. Could even put the slots on a slight slant... top, bottom, side, wherever.

Yes that is the idea. PeterW put me on to ready made spacers at Wickes which would make life quick and easy to drill a dozen or so holes in. I'll experiment. Thanks for all your suggestions though. 

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I have 5 of these stats and I do not appear to suffer any of the issues that you have. I spent a lot of time checking for the best location for 4 of them and also confirmed that they were suitably accurate with a couple of digital thermometers over a period of a few weeks.

 

Have you tried swapping the stat that is reading high for one that is reading ok to see if the problem moves with it? 

 

Heatmiser do a wall plate / surround for the V2 stat - not sure if it would help.

 

Edited by wozza
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