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Hot water circulation

 
Air Source Heat Pumps (ASHPs)
Last Post by DavidAlgarve 3 years ago
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 DavidAlgarve
(@davidalgarve)
Reputable Member Member
Joined: 3 years ago
Posts: 249
Topic starter 24/03/2024 4:20 pm   [#1449]

Perhaps not the appropriate forum, but some of your contributors may have some information.

I want to cut down on the amount of water wasted before hot water is available at the tap (kitchen, shower etc.). There are a few examples of small under sink pumps, possibly with a timer integrated, available in US and some other countries, but I can find nothing similar in Europe.

Has anyone any knowledge of anything similar?

Under sink pump

 


342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW


   
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 IanMK13
(@ianmk13)
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Joined: 4 years ago
Posts: 195
24/03/2024 5:17 pm  

I'm not sure that I understand quite what you mean. Since your thread title includes 'circulation', I assume you mean a hot water circulation system with a pipe from the hot water cylinder to the tap and a return pipe from the tap to the cylinder; surely there would already be a pump. I'm not sure how a timer would be used to cut down the amount of water wasted.

I have a hot water circulation system feeding the basins in my bathroom, shower room and W.C. which are conveniently located close together, but not so close to the hot water cistern. I have installed PIR 'occupancy sensors' in each of these rooms which powers the circulation pump as soon as someone enters. The PIR units each have a built-in delay which turns-off the pump after 30 seconds or so, by which time hot water will be available at the tap. More often than not, visitors to these rooms don't often want to wash their hands immediately on entering so the delay before the hot water is available is acceptable



   
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 DavidAlgarve
(@davidalgarve)
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Joined: 3 years ago
Posts: 249
Topic starter 24/03/2024 6:28 pm  

Thanks Ian.

The type of purpose-made unit I have in mind is on many YouTube videos and is fitted with T's into the hot and cold supply under the sink/ basin. There are a number of manufacturers, but I haven't found one yet outside the US and Australia

I believe they divert the hot water feed to the cold feed locally, until a set temperature is reached. Some kind of timer would make sense because you wouldn't want this to be operating at all times. Your solution with PIR's is superior, but my plumbing would not facilitate a multiple application and I may be looking to fit one of these simple units just in the kitchen or perhaps also in the No1 bathroom.

 I hope this link works for an example of what I have in mind:

 


342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW


   
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 IanMK13
(@ianmk13)
Reputable Member Member
Joined: 4 years ago
Posts: 195
24/03/2024 7:18 pm  

I haven’t seen these before!!
It may be that they don’t comply with UK regulations. 
In any case, you may save water but don’t you risk heating the cold water in the loft cistern?



   
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 DavidAlgarve
(@davidalgarve)
Reputable Member Member
Joined: 3 years ago
Posts: 249
Topic starter 24/03/2024 7:29 pm  

My DHW tank (heated from an ASHP) is on to ground floor and water displaced from the hot water feed pipework, would be pushed along the cold water pipe back to the DHW tank. Might have to make sure there are no check valves in that line!!


342sq m "Upside down" house in Algarve. Portugal
Mitsubishi PUHZ-120YUK 12kW ASHP
12 Solar Panels Growatt Inverter
2 x Growatt 7.5kW Batteries
Fronius EV Charger
Kia e- Niro 64kW


   
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