Heat Pump vs Solar Geyser

[Roy_ZA]

This is my 300l evacuated tube solar geyser's electricity usage for the current month (December, 0kWh) and last month (Nov, 31.3 kWh).

So yes, it works and it saves a ton of money.

View attachment 1205650
Rainy day today, so temperature not really going up (as opposed to yesterday this time when it was trending upwards).
View attachment 1205654

Love these graphs. What are you using to monitor it?

 

[SauRoNZA]

I have this beast:

View attachment 1205636

Costs R 35 000 (approx) to have it installed. It holds 270 litres.

This was my total usage for November:

View attachment 1205648

Hope this info is helpful.

**Edit: Forgot to mention that this is 100% self-contained, this does not feed water to a geyser.

Seems very expensive.

Then rather do this and go full on day/night with minimal power usage and can run off solar too.

Ecotop

GENERAL INFORMATION VERSIONS / MODELS NOMENCLATURE HOW IT WORKS CONTROL HEAT IS CAPTURED UNDER THE FORM OF SOLAR RADITION, ENVIRONMENTAL TEMPERATURE,...

www.energie.pt

Mine is being installed sometime in December/January and is about R40k and will be <4kw a day on 24/7.

Your heat pump setup actually doesn't seem all that economical compared to my normal geyser usage with a timer which did 203.93kw for November with 4 people on a 250L.

Mind sending the link? I had a look at their website but couldn't find it easily enough. It seems like 99% the same thing just without the thermodynamic panel on the roof.

 

[ebendl]

Why does your temp graph look so jittery?

Its an analog sensor, so tons of noise. I re-used the sensor the geyser came with and combined it with the analog input of a Wemos D1 Pro. There's only a resistor-based voltage divider in front of it, so no other signal filtering of any sort. I do run it through a moving average in Home Assistant (it's actually worse than this!)

 

[dj2381]

Seems very expensive.

Then rather do this and go full on day/night with minimal power usage and can run off solar too.

Ecotop

GENERAL INFORMATION VERSIONS / MODELS NOMENCLATURE HOW IT WORKS CONTROL HEAT IS CAPTURED UNDER THE FORM OF SOLAR RADITION, ENVIRONMENTAL TEMPERATURE,...

www.energie.pt

Mine is being installed sometime in December/January and is about R40k and will be <4kw a day on 24/7.

Your heat pump setup actually doesn't seem all that economical compared to my normal geyser usage with a timer which did 203.93kw for November with 4 people on a 250L.

Mind sending the link? I had a look at their website but couldn't find it easily enough. It seems like 99% the same thing just without the thermodynamic panel on the roof.

This looks pretty interesting, 40k will be a bit of a stretch though.

 

[Athos]

Seems very expensive.

Then rather do this and go full on day/night with minimal power usage and can run off solar too.

Ecotop

GENERAL INFORMATION VERSIONS / MODELS NOMENCLATURE HOW IT WORKS CONTROL HEAT IS CAPTURED UNDER THE FORM OF SOLAR RADITION, ENVIRONMENTAL TEMPERATURE,...

www.energie.pt

Mine is being installed sometime in December/January and is about R40k and will be <4kw a day on 24/7.

Your heat pump setup actually doesn't seem all that economical compared to my normal geyser usage with a timer which did 203.93kw for November with 4 people on a 250L.

Mind sending the link? I had a look at their website but couldn't find it easily enough. It seems like 99% the same thing just without the thermodynamic panel on the roof.

Kwikpump Domestic Integrated Heat Pump HP-300-V - HP-300-V

Combination of a hot water cylinder with a heat pump mounted on top. The hot water cylinder has no conventional electric element. Uses only ⅓ of the electricity of an electric water heater. Works in all weather conditions. Available in 150lt, 190lt and 270lt.

www.kwikot.com

That is the link for my heat pump. I must admit I am not using it as efficiently as I could be because I am running it 24/7 currently. Ideally you want to only run it during the day.

 

[ebendl]

Love these graphs. What are you using to monitor it?

This is all in Home Assistant.

Like said previously, the geyser's temperature comes from a D1 Pro running ESPHome and exposes the analog input as a temperature sensor. The rest is just Home Assistant monitoring it and logging it.

Usage comes from a CBI Astute connected to the geyser and talking to Home Assistant via tuyalocal for geyser control and power monitoring.

 

[RonSwanson]

Ja they are expensive. To be honest I didn't buy it, I bought the property with an old heat pump (same design). Long story short the old one burst and insurance paid for a like for like replacement which was this thing. I love it though.

It must have been under 5 years old then. Which insurance company was that, and under which policy?

 

[Athos]

It must have been under 5 years old then. Which insurance company was that, and under which policy?

The previous heat pump was installed in 2001 it burst in 2019 (middle of winter). I was with Santam at the time, I have no idea which policy but it was covered under the "geyser" insurance. It did take a few long cold days for me to convince them that this thing is a "geyser". Why are you asking?

 

[RonSwanson]

I am having a heat pump installed next week to run off my solar system. About R30k installation included for 5.3kw system (draws about 1kw when heating to 60 degrees celcius).

This is the last piece of my puzzle to move solar and the long and expensive process to reduce our daily consumption from around 26kw to 15kw

Based on experience with the heatpump at my holiday home they work great, but needs to be serviced annually. They don't like standing idle, which requires bi annual services. They are expensive though

My small no-name brand Chinese heatpump has contributed much to my own solar success story, the low current draw (3.1A / 760W) is ideally suited to a smaller inverter, and I get 2.8kW of heating power. A CoP of over 3.6 is hard to beat, and I always have hot water. Plus I pipe the cold air into my home on hot days, basically free aircon. Some days I give it a break and enable the 2.2kW standby element. It looks similar to @Athos unit, except that it's mainly stainless steel.

When it bombs out I will definitely spend the 30K to replace it, perhaps with one from EMS, or Enerflow.

 

[RonSwanson]

The previous heat pump was installed in 2001 it burst in 2019 (middle of winter). I was with Santam at the time, I have no idea which policy but it was covered under the "geyser" insurance. It did take a few long cold days for me to convince them that this thing is a "geyser". Why are you asking?

I am asking because I made specific mention of my heatpump in my conversation with my insurer (Auto & General at the time), and they told me that it was covered. When I received the fineprint documents from them, they had capped the "geyser cover" to 10K, so it wasn't worth much. The other pitfall I see is that after 5-7 years, and no major bursting incident like you had, if the unit becomes uneconomical to repair they may argue that it is "wear and tear", and not cover the full amount.

Edit: are you sure that yours lasted 18 years? 2001 - 2019?

 

[RonSwanson]

I have this beast:

View attachment 1205636

Interesting that the installation manual does not include anything specific on outdoor installation. My own unit is installed outdoors, granted that it is mainly stainless steel construction. I don't have ceiling space, so a roof install isn't going to fly. The day that I need a replacement heatpump, I need something that is at least IP65 rated.

 

[Arthur]

Talking about installation location, my heatpump is installed above the ceiling in the roof, above the main bedroom's bathroom, for shortest water route to most frequently used taps. There's fortunately plenty of standing room space.

The heatpump's low hum isn't really a problem. It"s set to be off from 22h30 to 06h30.

One of the best things I've ever done in house mods is having a dropdown trapdoor ladder installed. I used to hate having to get into the ceiling. A trapdoor ladder makes it so easy I almost look forward to it

 

[Speedster]

Talking about installation location, my heatpump is installed above the ceiling in the roof, above the main bedroom's bathroom, for shortest water route to most frequently used taps. There's fortunately plenty of standing room space.

The heatpump's low hum isn't really a problem. It"s set to be off from 22h30 to 06h30.

One of the best things I've ever done in house mods is having a dropdown trapdoor ladder installed. I used to hate having to get into the ceiling. A trapdoor ladder makes it so easy I almost look forward to it

That's interesting, speaking to a heatpump guy a couple of years back he said the ceiling is a bad option because there simply isn't enough heat available. Even though it gets hot up there, there isn't enough total heat due to the restricted volume. Do you find it heats the water sufficiently?

 

[Arthur]

Hehe. That "heatpump guy" didn't understand how heatpumps really work, nor the physics behind it. You don't need warm air for a heat pump. It works with cold air, even at zero C. Air we humans feel as cold still has oodles of heat energy, easily extracted in the Carnot cycle with the aid of an evaporator and compressor, like a fridge or aircon in reverse.

 

[Speedster]

Hehe. That "heatpump guy" didn't understand how heatpumps really work, nor the physics behind it. You don't need warm air for a heat pump. It works with cold air, even at zero C. Air we humans feel as cold still has oodles of heat energy, easily extracted in the Carnot cycle with the aid of an evaporator and compressor, like a fridge or aircon in reverse.

Is @agentrfr still around? IIRC he was knowledgeable on this front.

 

[Arthur]

Most people have fridges that can freeze to well below zero C. That is only possible if the "carnot engine" is able to extract heat from the freezer compartment to keep it below zero. A reasonable heatpump, especially if it has a variable speed compressor (using an inverter) will still make piping hot water when the air is minus 5 deg C, just take a little longer.

 

[Speedster]

Most people have fridges that can freeze to well below zero C. That is only possible if the "carnot engine" is able to extract heat from the freezer compartment to keep it below zero. A reasonable heatpump, especially if it has a variable speed compressor (using an inverter) will still make piping hot water when the air is minus 5 deg C, just take a little longer.

I'm no expert in the field, I'm just relaying what guys in the know have told me. There's a difference between what is possible, and what is optimal (especially since the whole point is to save electricity). Anyway, I'm sure someone far cleverer than me will be along to show which way the maths points soon enough.

 

[Athos]

I am asking because I made specific mention of my heatpump in my conversation with my insurer (Auto & General at the time), and they told me that it was covered. When I received the fineprint documents from them, they had capped the "geyser cover" to 10K, so it wasn't worth much. The other pitfall I see is that after 5-7 years, and no major bursting incident like you had, if the unit becomes uneconomical to repair they may argue that it is "wear and tear", and not cover the full amount.

Edit: are you sure that yours lasted 18 years? 2001 - 2019?

So it is a long story, we sat without hot water for 15 days in the middle of winter because of going back and forward with Santam. Initially they told me that they would not cover it because my geyser cover was only 5k. I pushed back saying that I must be covered in some way. After some "arguments" over the phone eventually they came with this thing about it being burst. So if it burst they would cover it and if not it was all on me (I didn't have 35k to replace it so I was going to just get a normal geyser in that case). So they sent out a plumber to assess and provide them with feedback regarding whether it was burst or not. The guys came out and said that typically these things don't burst because of the construction but mine had somehow burst. So I hit some luck there, they gave the feedback and Santam covered the complete replacement.

I have since moved away from Santam to outsurance because of some other issues. When I joined outsurance I tried to explain to them that I have a heatpump (once again they had no clue). Eventually they increased my geyser cover to 35k and I hope that I am now covered even in the event that it doesn't burst.

The previous owner of the property installed it and he told me he did it in 2001. I don't have any proof in writing though, I assumed he knows when he did it.

 

[RonSwanson]

So it is a long story, we sat without hot water for 15 days in the middle of winter because of going back and forward with Santam. Initially they told me that they would not cover it because my geyser cover was only 5k. I pushed back saying that I must be covered in some way. After some "arguments" over the phone eventually they came with this thing about it being burst. So if it burst they would cover it and if not it was all on me (I didn't have 35k to replace it so I was going to just get a normal geyser in that case). So they sent out a plumber to assess and provide them with feedback regarding whether it was burst or not. The guys came out and said that typically these things don't burst because of the construction but mine had somehow burst. So I hit some luck there, they gave the feedback and Santam covered the complete replacement.

I have since moved away from Santam to outsurance because of some other issues. When I joined outsurance I tried to explain to them that I have a heatpump (once again they had no clue). Eventually they increased my geyser cover to 35k and I hope that I am now covered even in the event that it doesn't burst.

The previous owner of the property installed it and he told me he did it in 2001. I don't have any proof in writing though, I assumed he knows when he did it.

OK, now it makes more sense, you got lucky

 

[Athos]

Interesting that the installation manual does not include anything specific on outdoor installation. My own unit is installed outdoors, granted that it is mainly stainless steel construction. I don't have ceiling space, so a roof install isn't going to fly. The day that I need a replacement heatpump, I need something that is at least IP65 rated.

Mine is installed outside close to the house so it has some cover (sort of). I am not sure what the IP rating of the thing is. I assume it is at least IP 44 otherwise you would absolutely not be able to install it outside.