Heatmiser Neostat v2 temperature sensor problem

[MJNewton]

17 minutes ago, pudding said:

Ideally I want all of my old neostats replaced with these new ones, free of charge of course! How best to go back to Heatmiser after their fob off email? Or just suck it up, 8years use is a long time and just buy new ones and replace as they fail?

 

I think their email has made it quite clear how long they intend/expect their product to last - and their willingness for discretion - so I can't imagine you being able to get anything further from them. The statute of limitations has expired too (6 years) so even if they were the supplier (and not just the manufacturer) a legal avenue of seeking recourse is no longer available.

 

Personally I'd be looking at other products, not least given this whole thread is centred around what a poor design this particular stat is (self-heating, poor ventilation to deal with this issue, limited longevity (for reasons as yet unknown) so I wouldn't throw good money after bad and would instead use the failures as the motivation to jump.

Edited January 12, 2023 by MJNewton

[ProDave]

Thanks for the pics.  No nothing obvious wrong.

 

In a situation like this I would do a web search to find the CEO of Heatmiser and address your complaint to him (her)

 

Say you have been fobbed off with the usual out of warranty reply.

 

Tell them you believe the original PSU design is faulty and you believe the design fault has been corrected with the new one with the ventilation.

 

Make it clear the stats themselves are okay and it is the back plate / psu that has failed and that is the part you need replacing not the whole thing.  

 

Let us know how you get on.

 

If you are brave, you could open up the new one and photograph the pcb and see if it is just the same with the addition of vents, or if it is a different design.

 

[pudding]

Yeah i'll try and take one of the newer ones apart to check and then chase them up.

 

Alternatives wise if it comes to that, exactly what would I be looking at and needing. Ideally I want something internet connected and preferably Home Assistant capable (I just a couple of weeks ago added HA and go the Heatmiser ones to show in there). This is the wiring center the current stats are connected to, just a rebranded Heatnmiser one I think - 

 

 

Also, while taking this pic of the upstairs heating, I noticed from this pic:

 

My flow and return temps are very similar, with both being just under 30, maybe return 1deg colder. My sons bedroom with 2 loops is currently on so there is flow through there right now. The manifold pump:-

 

was on the middle II setting, which I've just bumped up to 3 III. Was this the right thing to do, or would a slower lower pump setting actually help with the heat making into the floor there rather than being pushed quickly through the loops? (Sorry for the digression, just on a roll with the pics and spare time!)

Edited January 12, 2023 by pudding

[Bramco]

Be careful what you wish for in replacements. We installed some in our new build but had to replace them as the smartness couldn't be outsmarted.   We wanted to make sure that all our heating (it's a big insulated slab with UFH) was done in the really cheap 4 hour Octopus Go window.  The thermostats we first installed seemed accurate enough but would insist on starting up to an hour early - bless them. They wanted to make sure the rooms were up to temperature at the start time we'd set.  They got the boot - too intelligent for their own good and it was a function that couldn't be turned off.

 

Another annoying thing about them was the temperature display was very bright and couldn't be turned down, so annoying in a bedroom.

 

We've replaced them with Tado. You can at least turn off the 'early start' function on these.  They are battery powered, so couldn't suffer from the problem you've encountered. They connect to the internet through a dongle which needs to be plugged into an internet switch or your router - very low power comms protocol.

 

These seem to be functioning OK - except of course like all the thermostats we've looked at, they work in a very narrow temperature band ~0.2degs which means if you are controlling an ASHP the only way to get them to turn on and stay on, is to set up a schedule and put in target temperatures that would be hard to reach.  ASHPs are very efficient if they aren't turning on and off.

 

Simon

[pudding]

Thanks for the reply. These neostats have the same pre-heat type function. Can you name the stats you used. Could they be wires to the controller as in my pic above?

 

We've just moved over to Octopus, as I'm wanting to utilise a cheaper overnight window to fill our batteries and DHW tank and we have a 300L buffer tank for the UFH, (all from a GSHP) so no huge problem with a narrow temp window calling and stopping the call for heat frequently, although as you have done, I'd set it to target say 30deg overnight in the cheap window, so it gets the house nice and toasty overnight to hopefully last until the next nights heat up.

[SteamyTea]

6 minutes ago, Bramco said:

insist on starting up to an hour early - bless them.

Were they on GMT, or worse, BST?

 

If we put the world on UT/UT1, all these problems would vanish.

[Bramco]

1 hour ago, SteamyTea said:

Were they on GMT, or worse, BST?

Worse they were in their own time zone - anything up to an hour out - totally unpredictable.  The lovely lady in South Africa on the help desk suggested to be on the safe side setting the time in the scheduler an hour after we really wanted the heating to start. She agreed it was a pretty unworkable solution as we'd miss out on up to an hour of really cheap electricity.  

 

Smartness gone mad - it's not confined to things like thermostats either - we tried to buy a replacement iron recently but the model we have is now 'smart' so you can't actually set anything yourself in terms of steam etc.   Someone should set up a new brand 'NoSmart' - 'get full control like your gran used to have'.

 

Simon

[pudding]

Popped open one of the newer V2 stats. The PCB/PSU is slightly different, pics below. New one on the left, old on the right.

 

So, I'm guessing that adds more weight to the fact the original V1 wasn't great and has definitely been improved in V2.

 

 

[ProDave]

I would say same basic design but with the addition of a couple of extra components, possibly to meet a more stringent EMC or other reg that has come into force.

[Temp]

Can anyone see the pics @Pudding posted? I just see a No Entry sign for sale this on this page. Other photos on other pages are OK.

 

I'm on an Android tablet so I guess they could be a format it doesn't support?

[ProDave]

Showing for me.

[MJNewton]

They *were* working for me when first posted, but have now gone.

[TerryE]

 @pudding hasn't granted public access to the pictures.  If he grants access to specific (google) users then the image tags will show correctly for those users.  This isn't really a forum issue.  If you link to stuff that is inaccessible, then it is inaccessible

[dpmiller]

showing for me?

[pudding]

Hmm, I started by uploading them to imgur on my first posts on this thread, then noticed a copied link form google photots was automatically inserted into the thread. So, are the most recent photos direct from google not there for others? How do I grant public access to them, and how can some see them already but not others?

[AliG]

@pudding the people who can see them are signed into Google.

 

I have never used Google Photos but it looks like you can create a public link from there. I am not sure if the photos would appear if you insert a link or just the link would appear.

 

Or you can just copy the photos direct into a post.

[pudding]

Ahh ok, I'll not just copy in the link address to the photos in Google if only those signed into Google can see them then. I'll go back to uploading in Imgur, the filesize limit per post is too small I think for all the photos I've added. How can I go back and edit my posts though, the option isn't there anymore? Is there a time limit to editing for some reason?

Edited January 15, 2023 by pudding

[MJNewton]

I’m signed in to Google but can’t see them. Could when they first went up though.

 

Now that the edit window has closed just post them up again then we can move the discussion back on topic!

[pudding]

Take 2:-

 

Popped open one of the newer V2 stats. The PCB/PSU is slightly different, pics below. New one on the left, old on the right.

 

 

 

 

So, I'm guessing that adds more weight to the fact the original V1 wasn't great and has definitely been improved in V2.

 

[Temp]

Looks like minor changes but without a circuit it's hard to tell.

 

What's the temperature rating marked on the biggest capacitor new vs old?

 

Are the new blue round things transient suppressors or ?

Edited January 15, 2023 by Temp

[SteamyTea]

25 minutes ago, Temp said:

What's the temperature rating marked on the biggest capacitor new vs old?

My apprenticeship was at a company that made destructive testing machines.

One way to test a circuit would be to power it up and pop it in an oven at 100°C, then time how long it lasts, then pop another one in at 150°C and time that, finally at 180°C and time.

Plot results and you can hind cast to normal temperatures.

[Colliox]

Hi Ultima,

 

Just to note that I have experienced the exact same problems as you including the heating/cooling effect when the MVHR is turned on. I took a Testo DP440 meter calibrated to 0.5C with hotwire probe taped to a camera tripod and placed it directly below the temperature sensor on each stat.(with MVHR switched off) When the temperature settled I calibrated each Neo stat. The house temperature feels more balanced now. I also noticed that the stats run at 24C internally (measured with a thermal imager). I  tried to plug any conduit drops or draughty openings behind the stat with expanding foam to keep that temperature of the stat stable before calibrating. I had a stat in an attic room getting a bit of a draught cooling the electronics. Over all I'm still not happy with these stats. I have 11 in the house in total. I think I am going to replace them all with the Joule E91 stat which seem a lot more stable (currently testing one in the kitchen) The only thing is I will loose all Wi-Fi and app availability. By the way, in the bedroom the "calibrated" stat was reading 20.5C and the room felt really warm. I thought something wasn't right and to confirm my suspicion, the baby monitor alarmed at 24 degrees. These stats really have me driven mad.🙃

[Neo Stat User]

On 10/01/2023 at 10:30, pudding said:

Has anyone else had any complete PSU failures like me?

I had 7 of v1 Neostats installed about 7-8 years ago for temperature reading in a 9-zone heating system (2 zones use 1-wire temperature sensors). None of the 7 work all the time anymore: 5 have died at various points in the past 3-4 years after brief power cuts (screen totally blank), 2 of these start showing "--" for temperature after heating has been switched off for a day or so (if I leave the house for holidays so heating would only kick in if temperature went too low, so as to cause damage to the fabric of the building so to say - frozen pipes etc) - the thermostats fail to show the temperature much earlier than the temperature falling too low. These two then start showing the temperature reading figure again instead of "--" when the house has been warmed up sufficiently again (when it's quite toasty again for some time).

 

This is a product which has failed to report room temperature consistently, I'm not even using it for anything other than to provide temperature readings to my heating system via the Heatmiser API, so it's fundamentally not fit for purpose.

Edited March 10 by Neo Stat User

[athlonoc]

On 27/01/2021 at 21:38, Ultima357 said:

Now done all 11 (3 had remote sensors so not affected), recalibrated them and I now have much more stable temperature control, so very pleased with the result. As previously said, I measured the temperate of the top slot probing into the back. 29 degrees! Have sent a new design to Heatmiser. Given the large cost of tooling, I wouldn't expect them to jump on it though. Of course the slots would be on three sides, I just showed them how it could be disguised. 

 

I know this is an old thread, but after looking at temperature discrepancy issues between my old slimline v2 stats and my new replacement NeoAir V3 stats, they look very much like those as above which Ultima357 suggested Heatmiser should use. It's now 2024 but maybe he had something...... I hope they thanked you Ultima357 as it appears they listened to you?

[Ultima357]

3 hours ago, athlonoc said:

 

I know this is an old thread, but after looking at temperature discrepancy issues between my old slimline v2 stats and my new replacement NeoAir V3 stats, they look very much like those as above which Ultima357 suggested Heatmiser should use. It's now 2024 but maybe he had something...... I hope they thanked you Ultima357 as it appears they listened to you?

Nope, never heard from them again. I got into 3D Printing since then and designed a vented spacer and posted on Thingverse which others have since used to overcome the problem. Nice to know that they have finally seen the error of their ways.