The Homemade Heat Pump Manifesto - Page 177

randen · 10-17-15, 09:44 AM

Johnnypeste

Unless the current radiators are fan-forced there is not enough heat available to make your living space comfortable. The heat pump produces a water temp. around 40 Deg. C. And this may not be enough for a convection type of radiator. However a fan forced radiator may be enough but it would run longer on a low speed setting which may do the job and keep you comfortable.

I had installed a fan center (fan behind radiator)with DIY GSHP in my shop and its working extremely well saving a ton of money. I used to burn dinosaurs as well. Diesel $2800 for heat. Heat-pump less than $1000.00 for a year

Ground source heat pumps coupled with in-floor heating is the holy grail IMHO and is very economical. However the house must be well insulated and sealed against fresh air blowing through it. $2000.00 for a complete system even DIYed might be a little optimistic if you include the ground loop.

I'm not sure of your climate in Portugal but the Mini-split heat-pumps look very interesting.

As you are starting to understand we are entering an interesting time. Solar panels coupled to heat-pump keeping the family home warm.!!! Although its a little simplified in that statement but its now being done.

Randen

johnnypeste · 10-17-15, 10:07 AM

So for what i understood you are saying i should forget the radiators and gshp and go for n mini split heat pumps in each n division of the house? The climate outside is -10 C in the worst winter day. Its a pitty not being able to save the radiators...

johnnypeste · 10-17-15, 06:39 PM

Do you recommend any mini split brand in particular?

Mikesolar · 10-17-15, 06:51 PM

Don't get rid of the rads. Keep them as a second stage for really cold days. Turn the boiler max temp down to 50C and see if it will still provide the heat you need.. Oil usually needs a higher water temp but it all depends on how much m3 of radiator you have.

Use a Fujitsu or Mitsubishi ductless where you can, in the bigger rooms, You may need 2 of them for 200m2 house. These are be best performing units (highest efficiency) and the 3.5-4kw ones are the best. Really, you should have a heat loss done on the house to determine what size to use.

AC_Hacker · 10-18-15, 01:34 AM

Quote:

Originally Posted by johnnypeste

So for what i understood you are saying i should forget the radiators and gshp and go for n mini split heat pumps in each n division of the house? The climate outside is -10 C in the worst winter day. Its a pitty not being able to save the radiators...

Most people make the mistake of initially focusing on getting a heating source, rather than preventing heat loss. Retaining heat is less expensive and less damaging to the environment than creating heat.

The place to start is to quantify your heat loss. There are many ways to do this, but here is a pretty good way to do it for free:

Home Heat Loss Calculator

...the units are US, but conversion shouldn't be too bad.

Your biggest loss is usually air infiltration, then the next is insulation.

As I understand, your energy costs are twice what they are in North America. This make a big difference in your heating project. You should carefully consider the advice you get from this side of the pond, and calculate for yourself what makes best value for the money given your local economy.

From what I understand, higher-cost, but higher-efficiency heating systems pay for themselves faster where you live, than they do in North America.

The whole idea behind the Heat Pump Manifest thread, is that you can greatly reduce the cost of a ground source heat pump system if you do the work yourself. That is the reason that the thread you are now posting to was created, to encourage people to build their own systems.

'Randen' who is one of the people who responded to your question, is probably the best example of someone who has actually followed through and built his own working ground source heat pump systems. His system costs him about 25% per year to run, compared to what he payed before when he heated with oil. It was a lot of work for randen to do what he did, and he nearly gave up more than once. But he persisted, and now he has both the satisfaction of saving a lot of money each year, but also the pride in designing and building his own, unique system.

'Mikesolar' has years of experience in, and is very knowledgeable about the home heating industry in which he works, but to my knowledge, he has not built his own ground source heat pump system.

They both have great expertise in their past, that is highly relevant to your questions.

If you think you may be interested in building your own Ground Source Heat Pump system, this thread is for you, and you are welcome to be here, as this thread is for people who have made up their minds that they want to build a homemade heat pump system, and need help and advice to do it.

If you are considering a more conventional approach, that does not involve a homemade heat pump, I invite you to create a new thread where your concerns and ideas can be discussed by the entire EcoRenovator community.

I try to keep this thread, that I call the 'Manifesto' thread, focused on homemade ground source heat pump systems.

As far as I know, there is no other place on the entire Internet where Homemade Heat Pump systems are openly discussed.

I hope that you understand and respect the thread you are now posting to.

Sincerely,

-AC_Hacker

johnnypeste · 10-18-15, 04:06 AM

I understood this is a special project. I have made a direct question. If it was possible to use the same radiators i already have. It seems its not. Sorry for disturbing. Best regards

Pegasus · 10-19-15, 08:23 AM

Hello to all,

After many setbacks I finally made it to built my "proof of concept" GSHP.
My main concern was the output of the GS HX Loop (~ 500m of pipe, divided in 6 circuits and buried at ~ 2m depth under the house foundation). The main consept was to test the Ground Loop with the least amount of money, while getting in to the nuts and bolts of a GSHP.

The contraption is consisted by :
- Compressor : R22 2,9KW - 0.85 Ton from an old A/C (COP 3.5)
- Condenser : The A/C condenser coil submerged into a barrel where the Ground Loop water circulates (I can get a proper plate HX costs about 300 Euros)
- Metering Device : R22 Danfos adjustable TXV that can handle the compressor cooling capacity.
- Evaporator : 2 x plate HX ( I used both because they are small. Wrong e-bay order)
- Refrigerant : Initially R-22 then R-290
- Extras : LP+HP Safety switch, Refrigerant HX, Filter - Dryer (for R-407)

All welded together with awful craftsmanship (unlike randen) and put to the test.

During my GSHP study period I have found a very helpful book for beginners in the HVAC world like me (attached in the post). It is written for fridge truckers in plain English. It also has a very easy troubleshooting guide that the most experienced of you could quantify for R-290 GSHPs, check it out.

I am writing this because my main problem is that I can't lower SH below 6 deg C so that to use all of the Evaporator capacity. From the above troubleshooter my case is (most likely) the liquid line restriction and my best guess is the small orifice that I chose since I didn't took under consideration the increased COP.

As far as the Ground Loop, I believe it can handle a bigger compressor since the return temp is only 2 deg above the no load temp (25 --> 27) so it is a go for a proper set-up.

Any comments would be helpful.

P.S. There is a very nice "Refrigerant Slider" free app from Danfos that includes R-290!

paramax55 · 10-19-15, 08:32 AM

I have seen more and more posts with the idea of using mini splits. They are probably not the best choice for a DIY ground source heat pump. They are incredibly efficient and the off-brand ones are a fraction of the brand-name units. Yet they are not found all over the place and I figured there had to be a reason why. I asked a commercial AC guy (big company - high dollar) and my suspicions were confirmed. He said that they are noisy (I already knew that). While they can be reliable and last a long time, they can be troublesome when you first install them. When they break, there is also a shortage of people who can troubleshoot them and fix them. They are computer controlled and usually you have to find the bad board and replace the whole thing.

As far as hacking goes, it's all three phase motors. What you would need to do is rip out all of the electronics and install your own three phase motor controllers - similar to the idea of hopping up a modern sports car with twin turbos or something and controlling your engine with a "stand alone" engine management system.

The computer has algorythms to figure out how hard it needs to work to maintain a temperature in a room and then only runs at that level. It can balance the compressor for cooling (or heat) level, then balance the condenser fan for subcooling and evaporator fan for superheat. You would need to control these three variables for the level of heat transfer that you want.

This could be done if someone wanted to do it - anything is possible - but it's probably not good to jump in to that on the first try. There is so much more to a GSHP project that it probably makes sense to learn to crawl before learning to run. A hacked-up AC can be done so easily and cheaply that you wouldn't loose anything if you later switched to a mini-split and threw your initial project away after a year. But you would never do that.

The GSHP will be so much more efficient than other forms of heat transfer, you'll probably see no reason to go through the trouble of hacking a mini-split.

AC_Hacker · 10-19-15, 10:41 AM

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