Search with Wattson

Notifications

Clear all

Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!

ASHP using its immersion, but I don't know why

Tufty · 2024-09-04T18:02:18Z

Hi all,Each month I check my meter readings - on the heatpump and also my consumer unit.Ive never needed to use the ASHP immersion heater, so that figure has been 0 for a couple of years. But since Jan 2024, the immersion has been using about 5kwh per month; and has been progressing to about 11kwh last month.It shouldnt be using any immersion (especially becuase I only have DHW on in the summer months!). It didnt for the 2 previous years. Theres been perhaps one or two times where Ive has to quickly heat some water becuase Ive had guests to stay, but apart from that I just let the heat pump heat the cylinder once every 48 hours, which is fine for my use. (I live alone).Is there a setting somewhere that may be using the immersion?Heres some photos which Im hoping gives you an idea of its current settings. Any guidance or insight would be gratefully received. Thankyou.

Page 2 / 2 Prev

Air Source Heat Pumps (ASHPs)

Last Post by Mars 2 years ago

23 Posts

7 Users

8 Reactions

4,044 Views

RSS

Tufty

(@tufty)

Trusted Member Member

Joined: 3 years ago

Posts: 54

Topic starter 05/09/2024 5:10 pm

@gary Thankyou. At the moment I have it heat to 55 once every 48 hours. I will reduce that to 50 and see if that stops the immersion from kicking in. As you say, perhaps I fiddled with it in Jan 2024.

@Johnmo . Thanks all good points. Ill post an update on here when I have one. Thanks 🙂

ReplyQuote

Majordennisbloodnok

(@majordennisbloodnok)

Famed Member Moderator

Joined: 4 years ago

Posts: 1759

05/09/2024 5:45 pm

@tufty, I can confirm my Ecodan is set up pretty similarly; tank target temperature is 52degC and will start heating once the actual temperature drops below 42degC. That's plenty hot enough for our showers, baths and general washing up, even taking into account the periodic taking of residence in the bathroom by youngest (teenage) offspring.

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"

ReplyQuote

Tufty

(@tufty)

Trusted Member Member

Joined: 3 years ago

Posts: 54

Topic starter 06/09/2024 7:46 am

Morning guys.

Ive just been looking at the Ecodan. Ive reduced the DHW from 55 to 50 degrees. This is scheduled to happen once every 48 hours (as before).

Ive checked the immersion meter reading (it is separated out from the ASHP meter reading on my consumer unit). Its used 2kwh since sunday. The DHW came on monday and wednesday, and will do again today. This suggests that each time the cylinder heated this week, it needed to use 1kwh from the immersion.

I noticed that I have the DHW Max Operation Time set to 30 minutes. Not sure if that makes a difference? IE: Perhaps the Ecodan panics and thinks that its only got 30 minutes to heat the water up to 55 degrees, and so to achieve that within 30 minutes it uses the immersion? Just a thought.

Anyway, for now its set to 50 degrees. So Ill give it a few days and check the immersion meter reading.

ReplyQuote

Gary

(@gary)

Reputable Member Member

Joined: 3 years ago

Posts: 350

06/09/2024 7:49 am

@tufty

Posted by: @tufty

↑

I noticed that I have the DHW Max Operation Time set to 30 minutes.

That will be your problem then, just change it to 2 hours, its using the immersion as you have restricted the run time of the heat pump to heat the water so after 30 mins the heat pump switches off and it turns on the immersion to get it to the target temp.

ReplyQuote

Tufty

(@tufty)

Trusted Member Member

Joined: 3 years ago

Posts: 54

Topic starter 06/09/2024 10:40 am

@gary Great - I shall do this today. 🙂

ReplyQuote

Gary

(@gary)

Reputable Member Member

Joined: 3 years ago

Posts: 350

06/09/2024 10:48 am

@tufty Also make sure that you have the heating timer set up for that length of time as well otherwise the timer will cut it off as well but at least it won't try and use the immersion then it will just not get up to temp.

This one

ReplyQuote

Tufty

(@tufty)

Trusted Member Member

Joined: 3 years ago

Posts: 54

Topic starter 07/09/2024 8:35 am

Thanks @Gary - good idea. Ive just changed this setting to 2 hours. (it was at 1 hour). Cheers!

ReplyQuote

Tufty

(@tufty)

Trusted Member Member

Joined: 3 years ago

Posts: 54

Topic starter 19/09/2024 7:43 am

Morning guys

Just a quick update: My immersion hasnt kicked-in since I reduced DHW from 55 to 50, and increased DHW Max Operation Time from 30 minutes to 2 hours. So thats done the trick! Thanks so much.

Ive had to have a little word with myself: whats the point in keeping monthly stats if I dont notice that something like the immersion has been coming on since January! Ugh. Ive have been suitably self-admonished.

Anyway, thanks for your comments.

👍

ReplyQuote

Mars

(@editor)

Illustrious Member Admin

Joined: 5 years ago

Posts: 4516

19/09/2024 10:21 am

@tufty from what I understand, most low-temperature heat pumps can heat water up to around 45°C using just the heat pump itself. Anything above that typically requires the immersion heater, which might explain why it’s been kicking in when you’re trying to reach 55°C.

Nevertheless, I'm glad you've sorted it out.

For others that read this topic, your heat pump may be able to handle 50°C without using the immersion. If it still activates, consider lowering the hot water target to 45°C to avoid the immersion kicking in.

Get a copy of The Ultimate Guide to Heat Pumps

Subscribe and follow our YouTube channel!

ReplyQuote

Morgan

(@morgan)

Noble Member Member

Joined: 5 years ago

Posts: 698

19/09/2024 11:26 am

How does one discover/know if the immersion is being used?

Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.

2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.

ReplyQuote

Mars

(@editor)

Illustrious Member Admin

Joined: 5 years ago

Posts: 4516

19/09/2024 8:51 pm

@morgan It’s going to vary for everyone, but I see a significant spike in our SolarEdge app when the heat pump kicks in. Normally, our consumption for hot water heating via thevASHP sits around 3.5-4 kWh, but when the immersion heater activates, it jumps to over 5.5 kWh. I think it ultimately depends on how each person monitors their usage.

Get a copy of The Ultimate Guide to Heat Pumps

Subscribe and follow our YouTube channel!

👍

ReplyQuote

Page 2 / 2 Prev