Hey guys,

So currently I have a 1250w Heatpump. I want to add a solar energy system to the house.

Can I add a low pressure Solar geyser to the heatpump (in effect only using the heatpump in need at night) or is a low pressure solar geyser a no-no?

TIA

1 hour ago, TheoG said:

low pressure solar geyser a no-no?

Well this is an interesting question, I have never seen one connected to a low pressure geyser. If i take into consideration, the hardware available for and normally used in a retrofit, it tells me it is mainly designed for a high pressure geyser. All the schematics I have on file shows standard high pressure geysers. The heat-pump only circulates the water and I cant think of anything that will stop it from working accept for High pressure on the refrigerant side if no or too little water flows through the system. You might be faced with the same scenario as a blocked or partially blocked strainer. 

Then if you look at where a low pressure geyser is normally situated (Pretty high up a roof) to get pressure, you might be faced with some regulatory issues. Plumbing regulations allow for a maximum height difference of 3 meter between Geyser and Heat-pump as well as a max 8 meters sideways. (I am not sure why, but that is the regulations that was pass on in a course I have attended on heat-pumps a while back) 

If you dont have an answer by Monday, i will get into contact with my supplier and ask him if there is anything that will stop you from connecting it to a low LP geyser.

EDIT: All the above is said assuming the geyser has an extra port close to the bottom to be able to create a closed loop.  

Like Jaco said most heat pumps circulate water , so the short answer is yes . Check for a spare a way to plug in the temperature probe and if there is a port to circulate the water(I doubt there is) or see how you can adapt the plumbing to do so. You can T into the cold water inlet and find a way to return the water apart from the hot water supply outlet, maybe a T on the expansion side or banjo valve to replace the TP valve .

I can see why not , you will might need some one way valves. Here is an idea. 

most of it is to account for the push and pull of the pump as I am not sure what pressure it has. But also keep in mind that once the geyser is running you will only use the element for a very short time to top up the temps. So the heat pump might be an overkill. 

2 hours ago, PaulF007 said:

Here is an idea.

It looks like you have the one side of the heat pump on the low pressure side and the other side on the high pressure side.

I can't see why you can't just connect both to the low pressure side. Inlet side to the low pressure cold side (ie where the auxiliary (aka gravity pressure) tank flows into the bottom of the storage tank), and then the output side simple feeds into the top of the storage tank. Possibly with an anti-siphon loop, I'm not fully clued up on plumbing. Then the pressure on the inlet and outlet of the heat pump is the same and the only differential is whatever the pump creates... just as it would be in a high pressure system.

2 minutes ago, plonkster said:

simple feeds into the top of the storage tank

Well there is one issue with that. Heat pumps heat incrementally. So if you feed it water at 25°C (for example), it may spit out water that's only 30°C. Leave it running long enough, and it eventually gets the whole tank up to temperature. But I've heard many complaints from people who say their water goes cold within minutes of starting to shower... which is because the heat pump starts and starts spouting slightly-heated (aka cold) water into the top of the tank, right where the take-off is to the house!

Some heat pumps have a setup where they keep the water in a loop until it is hot enough to enter the tank (ITS for example). But again, this is an area I know little about.

On 2019/08/24 at 8:42 PM, TheoG said:

or is a low pressure solar geyser a no-no?

Hi Theo, I have aked the question to the head of ITS"s technical department and they came back with the following answer:

 

I hope this helps. 

Thanks for the info guys.... Seems like too much of a headache....

Might just try and sell the heat pump and go high press solar geyser then and get it over with. I've only had good experiences with solar geysers and my intention is to go off grid so I'll just need to manage the element usage.

5 hours ago, TheoG said:

sell the heat pump and go high press solar geyser then and get it over with.

Please dont sell it, just get a normal high pressure geyser and connect the heat pump to it. 1.25kw vs 3kw. Its a big advantage when going off grid. Heat pumps are really efficient, and I wont get rid of it  if I had one. I will make it work. 

I was intrigued to see an integrated heat pump in a geyser at Kwikot: https://www.kwikot.com/product-category/heat-pumps/integrated

Are these any different in operation re circulation?