Domestic hot water setup - Air Source Heat Pumps (ASHPs)

RE: Domestic hot water setup

Alfapat — Tue, 03 Dec 2024 15:51:02 +0000

@westkent OK , Interesting , Im surprised that Airsource only, is pushing to that level .

RE: Domestic hot water setup

Westkent — Tue, 03 Dec 2024 15:36:55 +0000

@alfapat .

I just set the water temperature to 60c via the systems MELCloud app.

As I’m still learning on these things how would I heat the water via the immersion if I’m not already??

9276

RE: Domestic hot water setup

Alfapat — Tue, 03 Dec 2024 15:27:42 +0000

So I have been looking at the tank sensor and as I have a spare sensor I compared the resistance and are both similar values. So cant be the sensor, I stuck a cake probe into the same location and it came to 1.5 degrees of the system sensor . So the controller is telling me 48.5 and home probe 47.1. Both the heating and Hot water valves were in the same position, I wasnt sure if it is closed or open , I suspect closed as I withdrew the system probe the HW valve motorised , detecting environment temp.

What I have done and I dont know if it will reach it, is move the DHW Temp up to 52 degrees.

RE: Domestic hot water setup

Alfapat — Tue, 03 Dec 2024 15:17:09 +0000

@westkent

Do you use the Airsource to keep your water at that level?

I didnt think this is possible to get it to stretch that far with out the immersion doing it ?

RE: Domestic hot water setup

Abernyte — Tue, 03 Dec 2024 14:49:34 +0000

Yes I certainly agree. The chance of legionnaires being a problem under those conditions is very low, with the usual caveats if there is someone in the household who is vulnerable to this or if the system has dead legs which are unflushed.

RE: Domestic hot water setup

Westkent — Tue, 03 Dec 2024 13:55:17 +0000

We heat the water up to the maximum of 60c.

Timed for 3am @ 6.7p.

Takes about an hour to heat and that’s when my heating cuts in at 20c until 7am when the low rate ends and the good lady leaves for work leaving the house empty. Heating down to 18c until 4.00pm then back up to 20c.
1 question..
I have turned off the legionnaires cycle as the water heating to 60c daily should take care of the legionnaires risk.

would I be right there?.

be interested in what people think on that front.

RE: Domestic hot water setup

Alfapat — Mon, 02 Dec 2024 19:22:10 +0000

Ok , thank you . Isuspected something like that but didnt want to believe it.

I had a problem where the heating valves and water valves were open to gether but wasnt affecting the temp too much , just the power it consumed was horric!

This I got sorted after finding someone who knew their job and the system was completely wired wrongly . I had this problem for some time as the company who installed the system went bankrupt and left me with a mess. Hopefully I can sort all this soon.

Best Regards

PAT

RE: Domestic hot water setup

Mars — Mon, 02 Dec 2024 16:12:18 +0000

@alfapat there's a fair chance that the sensor is not reading the temperature in the tank properly, or there's blending that occurs. We get that from time to time. Water feels very different coming out the tap than what the system is reading inside the cylinder.

RE: Domestic hot water setup

Alfapat — Mon, 02 Dec 2024 09:26:50 +0000

How much of a temperature drop should I expect between the tank and tap .

My system is Samsung gen 5 I think and the main controller is set to 51 degrees which is above the recommended 48 degrees , yet it only comes out of the tap at 42 degrees!

What if anything is wrong. This concerns the DHW system.

RE: Domestic hot water setup

Kev M — Sat, 04 Dec 2021 09:46:00 +0000

I would agree with what Derek says. Only heat your water at night if the unit rate is cheap enough to offset the reduction in COP. E7 rates are about 2/3 of daytime these days. There is likely to be little in it. If you have one of the really cheap rates, e.g. the Octopus 5p one, it may be worth it.

There is another factor though; ASHPs do HW or heating, not both. HW normally takes priority; when the HW starts, the heating stops. That means that your heating is off for 30-60 minutes or whatever, while the water heats. The water temp in the heating circuit and your room temp will both drop and the ASHP will have to work harder to catch up when the HW stops. It might therefore be better to schedule your HW for a time when the heating is either off or not working too hard.