ASHP and unvented Hotwater tank with Underfloor heating . Passivhaus. 170SQM . Who done it.

[joth]

33 minutes ago, Trw144 said:

In Loxone the mixing valve with PID control does the trick and solves the issue of overshooting/undershooting

Ah OK fair point - I was trying to think about implementing all the re-emptive adjustments the FTC makes (as it knows in advance what primary flow temp is about to hit the mixing valve). Great to hear the PID works well, I may yet employ it for the electric underfloor heating mats.

 

Anyway, I very much take Nick's point too that all the Loxone talk (and cloud-connected tanks) is well off topic here and that was my main point: Loxone is not needed to get this working really nicely ?

 

[Nick Laslett]

On 15/04/2021 at 09:02, PeterW said:

Just be aware for those looking at UVC for a heat pump, Telford do a 300 litre with twin immersions as a standard product for around £50 more.  
 

Single immersion

 

Twin Immersion

 

Telford are fully configurable to allow placement of the pipework where you require, and will also add additional pockets for around £30 each if you want more monitoring.  

 

 

I like the OSO tank for it’s standing heat loss. But the Telford’s seem much better due to more sizes, larger heat exchange, immersion placement and twin immersion. What is the purpose of having the immersion halfway up the tank in the OSO, vs at the bottom with the Telford? @ProDave made the point that having the immersion at the bottom gave more water for the Solar divert to heat. That sounds like a good thing?

[PeterW]

1 hour ago, Nick Laslett said:

I like the OSO tank for it’s standing heat loss. But the Telford’s seem much better due to more sizes, larger heat exchange, immersion placement and twin immersion. What is the purpose of having the immersion halfway up the tank in the OSO, vs at the bottom with the Telford? @ProDave made the point that having the immersion at the bottom gave more water for the Solar divert to heat. That sounds like a good thing?

Standing losses are negligible difference - the key one is Telford as standard will put all the connections where you want them. OSO is a standard product and you have to make it fit. @Nickfromwales will probably agree but when you want to run say cold supply >> tank >> manifold from left to right then you want the connections located differently to when the tank is in a corner. Same with immersion location and direction. 
 

Single immersion vs dual for diversion is questionable as you need a lot of diverted power to make a single take a tank up to 75°C and a dual allows you to do that in 2 steps for £50 which also allows you to boost just the top if you need to - very useful on a large tank. 

[SteamyTea]

On 15/04/2021 at 08:11, pdf27 said:

Heating from the bottom (or using the plate heat exchanger) means you de-stratify, and if you've got a relatively small heat pump (matched to a well-insulated house) you're going to have lukewarm water for some hours in the middle of the day.

Not my experience with my hot water. 

https://forum.buildhub.org.uk/uploads/monthly_2021_05/image.png.a202e32d89f5a9f2d49b7ef0a79302ab.png

Edited May 30, 2021 by SteamyTea