Reliable Hybrid Water Boiler with high Cost-Efficiency Ratio
 

Hello,

In this thread I would like to show my Hybrid Water Boiler that uses ground energy.
Hope this information will be useful.

The design of my energy efficient water boiler is based on GE's 50-gallon hybrid electric water heater.
In the below setup I use the Whirlpool's 40-gallon regular electric water heater as an extra tank and as a base to mount all necessary components. It also serves as a failover option, in case something happens to my hybrid boiler.

The heat pump's operating range is 7°C to 49°C (45°F to 120°F). If ambient temperature is outside of this range, the heat pump will turn off and the boiler will use electricity to heat water until the ambient temperature returns to within the operating range.

My basement's 6"concrete slab plays the role of a heat/cold exchanger. And when cool air ( 4°C-7°C), generated by the heat pump sinks, the slab absorbs it very efficiently.
During the heating seasons the ground temperature (temperature of the concrete slab in my basement) is very stable: about 10°C to 14°C (50°F to 57°F).

A large, unconditioned basement that is also perfectly isolated from seasonal temperature extremes represents one of the key elements of my success.

Boris Romanov

https://sites.google.com/site/modern...r_boiler-3.JPG

Nice job, Boris. Very good workmanship.

Did you take any photos of the construction of your unit?

I'm a little surprised that you switch from heat pump heating to resistance heating at 45°F. Although the efficiency gets worse at lower temperatures, the efficiency is better than electrical resistance heat, much lower. I would think that depending on your unit, it might be good to 35°F or lower.

Thanks for sharing your project.

-AC_Hacker

AC_Hacker,

Thank you for your comments.

I bought GE hybrid water heater for $950. The final cost will be $250 (after $400 rebate and $300 Tax credit). You can check all possible Rebates & Incentives for your zip code here: geappliances.com/heat-pump-hot-water-heater/

I received my $400 rebate check very quickly - just in two weeks:
https://sites.google.com/site/modern...400_rebate.JPG

In my opinion, this modern and energy efficient water heater is a real bargain. It costs less than the lowest price of a regular 50 gallon electric water heater ($950 - $400 rebate - $300 Tax credit).
But more importantly (based on GE calculation): “The investment return period is less than 1.5 years with application of federal tax credit and other state and local utility rebates.“ In my case the investment return period will be about one year.
You can get details about my project (including youtube videos) here: sites.google.com/site/modernwaterboilers ...


I agree with this part of your statement "the efficiency gets worse at lower temperatures..."...

Regarding your suggestion.
The heat pump's operating range ( 7°C to 49°C (45°F to 120°F)) is a factory default. Therefore I do not recommend to change these settings because of two reasons:
- warranty terms (we can play with The Water Temperature Setpoint ONLY),
- GE statement : " If ambient temperature is outside of this range, the heat pump will turn off and the boiler will use electricity to heat water until the ambient temperature returns to within the operating range."

In general, when temperatures of Entering Source Fluids (or Ambient temperatures) are higher - the COPs are higher too.
For example, Bosch Geothermal Heat Pump (Geo 6000 TW Series):
https://sites.google.com/site/modern...ERFORMANCE.JPG

So, instead of changing the operating range I would recommend to place hybrid water boiler (water heater) in the area with required ambient temperatures (proper operating range). It's clear, that such approach will lead to additional savings.

The video below is an excellent confirmation that my approach is realistic.
Video short description: This video shows, that during one hour of operation of the heat pump, the room temperature remained stable, because I installed my water heater in the basement - the large, unconditioned space isolated from seasonal temperature extremes.
Outside temperature was +17.2C
In this video the Heat Pump started to work in 2 minutes according to the algorithm (Unit self-check).
In one hour the humidity level dropped from 60% to 55%.

If my video is invisible in your Internet Browser - you can google these key words to find my video on You Tube: GE hybrid water heater - room temperature changes youtube.com/watch?v=ZBPDRJinauI

Boris Romanov

Boris,

OK, I see now.

I thought you had crafted the heat pump water heater yourself, no wonder it has such a 'professional look'.

There are some very resourceful people in this forum who have crafted their own heat pump water heaters from scratch, using materials that most people would haul away to the dump.

Needless to say, their cost was pretty favorable.

We all enjoys reducing resource use and saving money.

Best,

-AC

AC_Hacker,

Probably you forgot my initial statement: "The design of my energy efficient water boiler is based on GE's 50-gallon hybrid electric water heater."...

I support people who are trying to create something useful.
In fact, it is not too difficult to make GHP (water heater or furnace) at home. I found all components for the test-unit below on our local junk yard. Unfortunately, the compressor is old fashioned, too noisy and energy inefficient:
https://sites.google.com/site/modern..._heat_pump.JPG

So, there is no chance to make at home a RELIABLE hybrid water boiler for the extremely low final price, like in my case. In addition, I did not see any hybrid water boilers, that are powered by a concrete slab, but not expansive outdoor loops. That means my setup is original and unique.
In my opinion, the only modern GHPs with Scroll Compressors can compete with my setup in terms of cost-efficiency. Let's be realistic.

Boris Romanov

Whatever you say, Boris. I hope the GEospring unit serves you well. It has not had many rave reviews. The newer, R410a units have earned a reputation for losing their charge.

Looks like the unit in the above pic is missing a method of heat transfer for the evap coil. Concrete does not qualify as a heat transfer fluid, mainly because it is a solid.

jeff5may,

The unit above - is just a test unit to see an ability of concrete slab to absorb extremely cold air (-5.5°C - see thermometer) with little help (12V small fan).
And only after multiple tests I decided to demolish my oil-fired boiler...

Of cause, if your house is not perfectly insulated and you have to provide more BTUs - you have to use traditional types of heat exchangers.
Nevertheless, the above posted video is the good proof that my concrete slab is an excellent heat exchanger.

To understand how my idea is reasonable. you can see my electric bills here:
https://sites.google.com/site/modernwaterboilers/

Boris Romanov

"Reliable Hybrid Water Boiler with high Cost-Efficiency Ratio"
Why would anyone strive for a high Cost-Efficiency Ratio?

Your question was predictable to me.

Now is Olympic Games Time, therefore for this thread I used word HIGH in terms of pedestal of honor - the First place is the highest place. So, I am really proud of my achievement.

And as you can see here (https://sites.google.com/site/modernwaterboilers/) the original title of my web page is "Reliable Hybrid Water Boiler with an excellent Cost-Efficiency Ratio".

Boris Romanov

Boris,

Your basement temp changes (50°F to 57°F) are pretty standard for your area. So, there is nothing very interesting there.

Your language, "...perfectly isolated from temperature extremes..." is a little curious, since it is subject to seasonal temperature changes, but why use the word "perfectly"?

In my estimation, no seasonal temperature change would be "perfect isolation", but those few words are hardly worth the time to discuss anything.

My real question is are you just running your heat pump water as described in the installation literature, or did you modify it in some way that it is directly coupled to your slab?

If you are simply running it conventionally, what's the big deal? Xringer has been doing the same thing in his basement in Massachusetts for at least a year. However his small basement is getting pretty chilly in midwinter, due to :

• He has largly de-comissioned his huge oil burning furnace, which he call "The Tarm".
• He is absorbing heat energy from the basement via his heat pump water heater.

He was expecting an infinite supply of geothermal heat to forever keep his basement warmish, but over time it's gotten pretty chilly down there.

On the other hand if you have modified your purchased heat pump water heater so as to directly couple the evaporator to the slab, that would be pretty interesting to know about.

Best,

-AC