Heat Pump Sizing?

Spies

michaels said:

FreeBear said:

michaels said: Spent some of today finishing the replacement of the two tank immersions in the loft (one had long been not working and the other developed a thermostat fault) so replaced both, one of the new ones was obviously not brand new and was missing a connecter screw but managed to find a suitable one and then also added a wifi switch to this one

Be careful with some of those WiFi switches. Many of them only have a relay optimistically rated at 10A and should be derated to 5A or less. Ideally, for an immersion heater, you want to be using a contactor rather than a relay.

Claims to be 40A and even has a 'hot water' symbol on it.  Hopefully being only 13A and a resistive load it will be OK.  I do worry that in the roof space as well as the tank with immersions I also have a TV signal booster, lan switch, wifi hub, iBoost and now this wifi switch but no smoke detector!!!

This one:
Acmerota Smart Immersion Heater Timer Switch, 40A 2.4G WIFI Smart Wall Touch Boiler Switch Water Heater Timer Switch Works with Alexa Google Home and Smart Life APP Tuya : Amazon.co.uk: DIY & Tools

Edit:  Just seen it has had one scary sounding review added since I bought it!!!

Imagine that, some random Chinese brand not living up to expectations

FreeBear

michaels said:

FreeBear said:

michaels said: Spent some of today finishing the replacement of the two tank immersions in the loft (one had long been not working and the other developed a thermostat fault) so replaced both, one of the new ones was obviously not brand new and was missing a connecter screw but managed to find a suitable one and then also added a wifi switch to this one

Be careful with some of those WiFi switches. Many of them only have a relay optimistically rated at 10A and should be derated to 5A or less. Ideally, for an immersion heater, you want to be using a contactor rather than a relay.

Claims to be 40A and even has a 'hot water' symbol on it.  Hopefully being only 13A and a resistive load it will be OK.  I do worry that in the roof space as well as the tank with immersions I also have a TV signal booster, lan switch, wifi hub, iBoost and now this wifi switch but no smoke detector!!!

This one:
Acmerota Smart Immersion Heater Timer Switch, 40A 2.4G WIFI Smart Wall Touch Boiler Switch Water Heater Timer Switch Works with Alexa Google Home and Smart Life APP Tuya : Amazon.co.uk: DIY & Tools

Edit:  Just seen it has had one scary sounding review added since I bought it!!!

Would be worth popping the front cover off and taking a peek at the relay - I have a number of smart light switches that are of a similar size, but the case is no way big enough for a 40A relay.

QrizB

FreeBear said:

Would be worth popping the front cover off and taking a peek at the relay - I have a number of smart light switches that are of a similar size, but the case is no way big enough for a 40A relay.

OTOH I've taken one of these apart and it does have a 16A nominal-rating relay in it.
https://www.aliexpress.com/item/1005002278683118.html
Currently have one controlling my immersion heater. No problems yet ...

michaels

Up thread is was asking about 'pockets' for heat meter temp probes.  I now have these two items which make a pocket but will fit an 8mm probe and mine is 6mm - I am wondering if I should add a thermal medium to make sure the probe reading is mode accurate and was wondering what liquid I should use?  Could try thermal paste but it would require more than the few drops you normally use.

Made4Trade Compression Reducing Tee Fi 22mm x 22mm x 1/2" Fi | Toolstation

Thermowell Immersion Sleeve Pocket for Temperature Sensor 30-200mm Thermocouple | eBay

FreeBear

michaels said: Thermowell Immersion Sleeve Pocket for Temperature Sensor 30-200mm Thermocouple | eBay

If you have this one in your hand, the description says 6mm internal diameter and 8mm externally. If it really is 8mm internally, a good dollop of thermal paste will help.

QrizB

michaels said:

I am wondering if I should add a thermal medium to make sure the probe reading is mode accurate and was wondering what liquid I should use?

If it looks too big a job for thermal paste, a drop of 10W40 or whatever lube oil you have around the house would probably be sufficient.

michaels

Thanks both, I haven't actually tried so it may not be as big a problem as I thought, probably I job for xmas hols now along with fitting a magna trap. 
I have insulated with the foam insulation plus duct tape, the duct tape seems to not stay that sticky outside so may have to look at another tape to keep all the insulation in place.

Can add some pics if people are interested?

Reed_Richards

michaels said:

Can add some pics if people are interested?

Sure, I'd like to see pics.

FreeBear

michaels said: I have insulated with the foam insulation plus duct tape, the duct tape seems to not stay that sticky outside so may have to look at another tape to keep all the insulation in place.

I use cable ties, lots of cable ties with pipe insulation. The heat from the pipes would soften the adhesive on duct tape, so no real surprise that it falls off.

QrizB

I was speaking to a neighbour who's having a heat pump installed right now (OK the crew might've gone home for the night) in his 4-bed semi. He's getting a 12kW Daikin but thinks the surveyor over-egged the heat loss calcs so there's a chance he'll run into the same sort of problems that @matt_drummer had with his.

Should be commissioned by the weekend so I might wander over then and see how he's getting on.

I won't say what he's paying for it, but it's a lot more than any of the Octopus quotes I've seen on this board!