Buffer tank on heat pump - element not heating

[townlema]

Does anyone know why on my air hear pump buffer tank the backup heating element is not heating the flow water. It’s a 3 phase element that is receiving voltages and is drawing 4.5kw but the water heats up a tiny bit and very slow. The buffer tank is 100litres.  Any help gratefully received. 

[JohnMo]

Sounds like you could have a big heat demand, if it's all 3 phase and you have a 100L buffer.

 

Depending on the heat demand and the immersion rating they may not be matched well.

 

More info required.

 

Flow rate

Immersion size

Heat required

[Temp]

2 hours ago, townlema said:

4.5kw but the water heats up a tiny bit and very slow. The buffer tank is 100litres

 

If I've done my sums right..

 

4.5kW = 4500J/S

Water needs 4200J to raise 1L by 1C or 100L by 1/100th of a degree.

 

So with no heat being removed/lost I would expect a temperature rise for the whole tank of about 1/100th of a degree per second. Perhaps a bit faster.

 

So a 10C increase would take about 1000 seconds or 15-17 mins. 

A 50C increase from 10C to 60C would take about 75-85min.  

 

If any energy is being taken out at the same time that could extend the warm up time dramatically.

 

[SteamyTea]

1 hour ago, Temp said:

If I've done my sums right..

 

4.5kW = 4500J/S

Numbers are right.

 

You have an S for siemen, electric conductance.

Should be lower case s, for seconds, which is part of the time, t, family.

T is, in this case, the SI sign for time, because it is at the start of a sentence, but this T is now temperature (sometimes), as T can also be for tesla, magnetic flux density.

 

Really annoying that autocorrect changes things.

 

Edited November 15, 2023 by SteamyTea

[Temp]

Darn it, arrested by the unit police. Guilty as charged your honour 😄

Edited November 17, 2023 by Temp