Samsung Gen6 ASHP, 40kw used in a day (HW only)

[Andehh]

We have just moved into a new build, with a Samsung Gen6 ASHP, 300L cylinder and a heatmeiser controller. New build with Building Regs +20% insulation standard, meticulously checked by myself during the 2 years of construction.

 

Joules came out and 'commissioned' it last week in the most casual of fashions. They set it up, shrugged off my requests for what I wanted, I didn't fight them for it (because we were moving in at the time) and they went on their way. I figured I would adjust it after the fact.

 

The only thing I have changed since then, is for the legionnaires cycle to be done during the day between 12 and 5pm on a Wednesday, when we are out & to maximise the 4kw of PV we have. It's set to 55 degrees for this (by Joules) on an otherwise 50degs cylinder temp.

 

The last several days we use between 4 - 6kw for the DHW which im fine with...however the first legionnaires cycle yesterday used 38kw (!!!) and as far as I can tell it never hit 55 degrees. I also woke up to an error message this morning (e919)  which when I googled it came up as the legionnaires cycle not hitting the desired temp.

 

I simple cannot figure out where this 28kw went..... as the cylinder 'only' hit 50 degrees odd and the heating never came on....but that energy went somewhere.

 

 

apologies, it used 28kw not 38kw!!

 

Edited July 6, 2023 by Andehh

[ProDave]

First question, what temperature is it heating the water to? (what did they set as the target temperature)

 

40kW is about what i use in a whole week for hot water in the deepest depths of winter when there is no solar PV to help it, and the incoming mains water temperature is very low.

 

The legionairs cycle will almost certainly use the immersion heater.  One possible problem is the immersion thermostat is set too low, and that cut out before it reached temperature.  But agreed the energy would have gone somewhere.

 

 

[Andehh]

normal cylinder temp is 50 degrees, legionnaire cycle is set to boost it to 55 degrees. Cylinder controller is set to ''standard'' mode.

 

Edit; sorry it is 28kw not 38kw. Which is still a lot on a warm, sunny day when the temp wasn't stone cold beforehand.

 

 

Edited July 6, 2023 by Andehh

[eniacs]

When you returned was the house boiling hot, as though 38kWh of heat had been dumped into it through the radiators? There's not many other places for 38kWh to go in a house without noticing it. Down the drain?

 

 

[Andehh]

nope, we are fully occupying the house and I was around all day yesterday. Heatmeiser isn't showing any surprising warm ups of rooms.

 

I was in and out the utility room all day, and cant say I noticed much that was suspicious. 

 

I have reset the legionnaires cycle to run again today (12 to 5pm) to see if it replicates it.... but i am still keen to get to the bottom of it!!

Edited July 6, 2023 by Andehh

[JohnMo]

Why are you running the legionnaire cycle for 5 hrs? You only need for a hour, if you are constantly using water i.e. daily there is a question if you need it all. Are you trying to get the cylinder up to 55 degrees with ASHP or with an immersion?

 

DHW heating, if you have target temp set to high, that the ASHP cannot hit first time, what happens is the heat pump will keep trying and short cycle for many hours until it gets there. During this time it will use a colossal amount of electricity (kWh).

[Andehh]

Thanks John.....!

 

I have gone back through the menu and the duration was actually set for 15mins, with a max time of 3 hours (so i figure it will spend 3 hours trying to hit the temp then give up and/or succeed).... so I am wondering if that's what has caused the issue.....It was using 15min slots to try and hit the temp...burning energy but not actually making a material difference to the temp?

 

I have it set to go on again this afternoon, with an hour duration starting at 2pm with a max duration of 3 hours. Hopefully that sorts it??

[eniacs]

Maybe its a recording error? 3 hours and 28kwh seems impractical, thats a constant load of 9kw. Whatever it was would be glowing!

[DanDee]

1 hour ago, Andehh said:

Thanks John.....!

 

I have gone back through the menu and the duration was actually set for 15mins, with a max time of 3 hours (so i figure it will spend 3 hours trying to hit the temp then give up and/or succeed).... so I am wondering if that's what has caused the issue.....It was using 15min slots to try and hit the temp...burning energy but not actually making a material difference to the temp?

 

I have it set to go on again this afternoon, with an hour duration starting at 2pm with a max duration of 3 hours. Hopefully that sorts it??

Take a meter reading and compare with what the HP displays.

[DanDee]

maybe the metering setting are not right

https://midsummerwholesale.co.uk/pdfs/ehs-install-guide-samsung.pdf

[eniacs]

27 minutes ago, DanDee said:

maybe the metering setting are not right

https://midsummerwholesale.co.uk/pdfs/ehs-install-guide-samsung.pdf

 

 

Good spot that!

[Andehh]

Thanks guys, I think it might have been the short cycling. It looked to only be using the immersion heater for the legionnaires, which when combined with 15min durations would lead to huge energy usage without actually warming up the water I think?? 

 

Either way I've turned off the legionnaires function, to see if it happens again without it on. If nothing over the next week, I'll turn it on again with the duration set to an hour maybe. 

[ReedRichards]

Short cycling is the bête noire of boilers and heat pumps but it's not nearly so terrible as to lose 28 kW of electricity (so at least 28 kW of heat) to nowhere. 

[eniacs]

1 hour ago, Andehh said:

Thanks guys, I think it might have been the short cycling. It looked to only be using the immersion heater for the legionnaires, which when combined with 15min durations would lead to huge energy usage without actually warming up the water I think?? 

 

Either way I've turned off the legionnaires function, to see if it happens again without it on. If nothing over the next week, I'll turn it on again with the duration set to an hour maybe. 

No it wouldnt. Your heat pump cant consume 28kwh in 3 hours, not unless it heats a block of 15 flats. The compressor will be 2-3kw max so max for 3 hours would be 9kwh. There must be a measurement error somwhere

[Christiano]

We have a Samsung AE160RXYDEG, make sure the schedule for Legionnaire’s isn’t on heating method Economic as the immersion won’t come on and if you don’t get a high enough flow temperature you’ll never get it to 55 without the immersion.

 

In the summer I don’t bother with Legionnaire’s as the iBoost keeps it in the 60s most of the time (except recently!).

[Conor]

If it's an unvented system, turn the legionaries cycle off, really not needed with treated mains water. And try your setpoint at 45c, rather than 50c. 

Edited July 8, 2023 by Conor

[Andehh]

Thanks all. Yes, I have just turned legionnaires off, felt the simplest solution. 

 

For some reason with joules, I can't reduce the hot water from 50degs as that's their lowest coded set point. 

 

As for the "economy" mode, I don't get the choice to adjust this for legionnaires, only the temperature, duration time max duration time and temperature. Joules shrugged off the energy usage is "fine", but their technical help definitely felt as a "system is infallible, just ignore it... I'm sure it's fine" rather then actually understand the qwerks.

[SteamyTea]

I suspect it is a recording error on the meter.

As other have said, something would be very hot.

 

Can we also get kW and kWh sorted.

There is a big difference between power and energy.

 

 

[RobLe]

Perhaps the heatpump doesn’t actually measure consumed electricity, but estimates it based on software expectations.  If the immersion is bust, it could keep trying, never achieve much, but believe it has used lots of energy in the process.

Next time you want to give it a go, check your main house elec meter before and after, as a sanity check.