# Samsung Heat Pump Joule Kodak DHW Tank Temperature Dropping when no Drawing of water

**URL:** <https://community.openenergymonitor.org/t/samsung-heat-pump-joule-kodak-dhw-tank-temperature-dropping-when-no-drawing-of-water/29424>\
**Category:** Heatpump\
**Created:** [21 November 2025 15:20 UTC](https://community.openenergymonitor.org/t/samsung-heat-pump-joule-kodak-dhw-tank-temperature-dropping-when-no-drawing-of-water/29424 "2025-11-21T15:20:40Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![SarahH](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/sarahh/32/27116_2.png) [@SarahH](https://community.openenergymonitor.org/u/SarahH)\
**Post date:** [21 November 2025 16:24 UTC](https://community.openenergymonitor.org/t/samsung-heat-pump-joule-kodak-dhw-tank-temperature-dropping-when-no-drawing-of-water/29424/2 "2025-11-21T16:24:48Z")

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Hi @Fquinn28, and a warm welcome to the forum.

> [@Fquinn28](#):
>
> When the DHW is heating up in the Summer time the DHW Temperature can drop from 40 to 30 degrees before starting to heat up again to 45 Degs although the tank does hold it Temperature well in the summer months, why is the DWH temperature dropping so much ?

This depends on your set-up (the physical layout, and your DHW heating settings). What you are seeing may be no more than a little temperature layering in the DHW tank (which in general they are prone to do, though I can’t speak of the Joule-Kodiak specifically). If just a little hot water is drawn off, and the temperature probe is near the bottom of the tank, then the cold water that enters may affect the measured temperature (while most of the tank is still hot). If you have set your DHW heating to, say, only once per day for an hour, the tank will sit there with cold at the base, warm everywhere else, until your next heating session.

> [@Fquinn28](#):
>
> Now were in the winter i’ve noticed the DWH Temperature drops down maybe 2, 3 times a day depending on the outside Temperature to reheat the tank, this happens after the water has been heated up to 45 Degs in the morning and no draw of water off during the day while at work.

There are a couple of controller algorithms that run in the background (and there’s not a lot you can do about it).

If your circulating pump hasn’t run for an hour, and the outside temp is below 5degC, the circulating pump will run for a few minutes, via the DHW tank coil, to make sure that the outside piping doesn’t freeze. This results in a temperature drop in the DHW tank. Have a read of [Samsung Gen6 and anti-freeze pump cycling below 5C OAT](https://community.openenergymonitor.org/t/samsung-gen6-and-anti-freeze-pump-cycling-below-5c-oat/29145) for an animated discussion on the subject.

Also, if the circulating pump hasn’t run for 24 hours, the controller “exercises” it for a few minutes to make sure it hasn’t seized (though I forget whether this is via the DHW tank coil or the emitter circuit).

Finally, there are defrost cycles. These take heat from either the DHW tank or the emitter circuit, depending upon which was in use at the moment the defrost cycle started. See [Samsung R32 ASHPs - when is a defrost not a defrost?](https://community.openenergymonitor.org/t/samsung-r32-ashps-when-is-a-defrost-not-a-defrost/27553) for further explanation.

I do hope the above doesn’t confuse you further (or try to teach you to suck eggs…).

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