Whole house heat pump
 

Hey All,

My name is Ben and I'm pretty excited to find this message board.

I have been trying to figure out how to build/buy a whole house heat-pump.

I could get a Daikin Altherma and that would cover hot water/heating/cooling but it sill misses refrigeration.

I would like to have a split system that also runs my refrigerator.

Anyone have any suggestions or ideas?

Thanks,

Ben

I have not heard about a system that could run a refrigerator too..

Seems like it might be wasteful to crank up a large heat pump (20 to 36k BTUh),
on a nice mild spring day, just to run a refrigerator..?.

If you wanted run your refrigerator for a low cost, there are hacks that will work..
Plus, there's always Solar PV.. A small off-grid system maybe?

During the summer, there are many days when were are not cooling or heating. So, our systems stay off..
But, we always need hot water. So, our hot water system is a stand-alone system..

We use a small heat pump as the main hot water maker, and also use some
solar PV panels to provide much of the hot water on sunny days.
You can buy a hotwater tank with a build-in heat pump..

Yes, I may be out of mind. What I liked about this board is that it seemed like there was an acceptance of foolish pursuits.

My thinking is that when considering the whole house I will find efficiencies. I mostly want to constantly be routing the need for heat and the need for cool around the house constantly all day.

It could be I should just try to marry a hot water heater to a refrigerator and then look for ways to tie that into a larger heat-pump.

Nope, a lot of these guys are resistant to "foolish pursuits"..:rolleyes:
Like when I connected the heating elements of my hot water tank directly to solar PV panels. :p
Most people think it's a waste to use PV to heat up water.. Not efficient. At all.
But, it does work. Pretty well in fact.

Temperature control, turned into a problem, since the tank tends to over heat when solar is too good..
The other day, it was super cold here, and the sun came out.. My hot water
tank zoomed up over 170F.. I had to cool it down..
Normally there's no problem, but PV works much better in extreme cold..
In the summer, I just disconnect one of the arrays for a few months.

The whole house efficiency idea is what I was looking at when I ordered
a 24k BTUh mini-split ASHP. It worked!
But the den (addition) on the back of the house has so much glass, we installed a second mini-split for the den..

After seeing how both of Sanyos work together, I'm starting to think a house
with a 3 or 4 heating zones, could be handled by 3 or 4 mini-split units..
Because, the smaller BTUh units use less power/per BUTh and can work at lower temperatures..
Right now, one of my Sanyos is down. Needs repair.
But, the other Sanyo is doing a pretty good job doing the whole house..
(The den is still a little cool).

So, what happens when it's 97F or 9.7F and your Whole house system goes down?
If you had bunch of small 9k to 12k BTUh 20-30 SEER units, one of them going off-line won't be a big deal..

GREE Terra 9,000 BTU Ductless Mini Split AC FREE 15' Line Set

27 SEER / 14.5 EER / 9.0 HSPF Thems some good specs! :D

I think you have guessed right.

These combined forums are infested with dreamers and fools, and with a few practical folks to keep things occasionally reasonable.

You will need to start thinking in energy units, like kilowatts for starters.

Do some poking around about water heaters, and your water heater in particular. You need to know its power consumption over time, like a month perhaps.

You'd also need to know about your typical heating and cooling requirements over time, in the same units (kilowatts) so you can compare.

If your house is monumentally low-performance (leaks lots of heat & cool), compared to your water heater, then the marginal gains that could be made by combining your water heater, would not be worth the trouble. In this case, you should direct your project energies to improving your house thermal efficiency, starting with infiltration...

But if your house is very tight and very well insulated, and the difference in scale between house energy and DWH energy is comparatively small, then it would be prudent to continue your quest.

Best,

-AC_Hacker

We have a existing mini-split a single compressor and 3 different zones/indoor units.

We actually have spread them across 2 buildings with underground connections.
It is a pretty good system but this weekend I bet it wouldn't have heated the house. We installed them for air conditioning and use it for heating during the shoulder months.

The Daikin Altherma has an electric element for when it is too cold for the heat pump. Which wouldn't help with refrigeration.

The good news is that I have been spinning my wheel on this thinking for a while and actually have a lot of the figures you say I will need.

We actually have 2 other buildings that are well insulated on the property. I currently have a centralized utility room in the house of the basement which has 2 natural gas boilers. One is steam for the radiators of the house and the other is hot water for radiant heat in of the out buildings and low temperature baseboard for the other building.

When I was planning the heating for the 2 other buildings I did all sort of heat-loss calculations. We also recently installed a PV solar array that I did all sorts of calculations.

I guess I should comb the site more and come up with a small project to get my feet wet.

I got hooked on the site seeing all the dehumiders being turned into water heaters.

Thank you for the the thoughts.

Ben

Welcome to the forums, Ben! You will find there are plenty of open-minded, creative thinkers here that can help guide you in your endeavors. I encourage you to start pouring through the forums and reading past threads relevant to your situation. There are literally mountains of information at your disposal.

The dehumidifier-turned-water-heater would be a good engine to retrofit an existing refrigerator into your boiler loop. The external heat exchanger could be rerouted to a refrigerant-to-water condenser hx, which could dump the waste heat into your boiler loop. It would only add a thousand or two BTU per day, but it could work. Whether or not it is worth the effort is all up to you, but it would give you some experience and confidence to move into the full-sized realm.

Tell us more about the multi-zone, multi-temperature boiler loop setup you have running. Natural gas use is incredibly easy to track and log, so if you have been operating this rig for a few years or longer, you should have some good historical data. Even if you have only one gas meter, and haven't been logging each zone's usage. Your gas bills will tell you volumes with respect to system retrofit or supplement options. Due to the fracking craze, natural gas is incredibly inexpensive as an energy source today. Like all good things, they will end eventually, so it is a great idea to have another energy source to fall back on when this eventually happens.

Are you considering an air source or ground source heat pump?

I have a NIBE GSHP. The pipe coming into the house from the underground loop passes along the outside of a basement cool room / cold store. Had I thought about it at the time of installation I would have had it run through the cool room. Currently the incoming fluid is around freezing so it would have been a good & cheap way to cool that room and any heat extracted from the room would have offset the heating costs for the rest of the house. I may still try to somehow use that pipe to cool the cool room.

The manual for my heat pump has a section on "free cooling" which I assume could be also used for something similar. It doesn't give details though. All it says is:
http://ecorenovator.org/forum/attach...1&d=1455691255

Hey All,

Sorry I dropped out for a bit. After my last post I resolved to buy a Daikin Altherma system.
Only to find they are no longer available in North America. After more searching and pleading with various sources the mostly likely story is that they have a 3rd generation model that they are trying to get through UL certification. They stopped bringing in the first generation won't bring in the second so we must wait for the third generation. I don't know if it is true but I will choose to have faith.

To answer some questions.

My set-up is unusual. I live in old plank new england farm house 25'x25'. That happens to have a 7 car garage 60'x24', carpentry shop 25'x30', 13'x30' "school bus garage". All from around the 1920's.

All of the boilers, solar inverters, power, network are in the basement which is a maintain room. We have a Daikin outdoor unit in the far back corner of our lot that has underground tubing and branch points in various buildings so that all the split tubing is concealed and I have a single hidden location for the outdoor units. I also have an additional line set for a Daikin Altherma system that doesn't exist going from this location to the basement 120' away. Currently a gas fired boiler heats up water and pumps it through insulated pex tubing that is buried underground connecting the 7 car garage and the house.

The 7 car garage has more or less 22' x 10" x 59' thermal mass made of masonry sand. This has the appropriate insulation and pex-al-pex tubing. There are times during the heating season when my return water is hotter then my input water.

The carpentry shop has a perimeter with 98' of rental UF-2 low temperature baseboard. The more baseboard surface area the lower the water temperature that can be used. This office also has a Daikin for AC/heating.
I tried to post link for runtal radiators but I need one more post.

Both the buildings are connected together in the garage using a single main loop that is fed by the builder in the house. The main loop also has 1" pex-al-pex connection to the "school bus garage" where I may put solar thermal collectors.

I have done various logging and at this point I can comfortably say that the carpentry shop has negligible impact on my heating. bill.

I believe that my set-up will greatly benefit from a very steady 95-110 degree hot water source.

@Jeff5May you could see how with my thermal mass generate a couple of BTUs a day might add up if I start in aug.

I'm considering an air source heat-pump the COP on hot water to meet my needs when it 13 below F is still over 1 and it will be around 3 most of the heating season.

So what am I going to do. I found that Daikin Altherma line now contains a chiller that looks like it runs off hot water.

We have a PV array and I'm considering expanding to meet the projected load of the Altherma system. I think I'm going to try for net-zero by large solar array and high-surface area of low water temperature. The real trick will be replacing the steam boiler that heats the plank farm house.

Wow, what a load of information! Please post some pics or drawings to keep everyone's feet on the ground. There is WAY too much described here to not imagine some kind if "Chitty chitty bang bang" sort of living arrangement. I do see you made no mention of a windmill... Sounds like you have quite a unique setup installed and operating already.


The garage is very interesting to me. The way you described it makes it seem a good fit for annualized heat storage. The mass and insulation are there, as is the conduit for heat transfer. Usage and comfort may be compromised during certain situations, so it depends on how much it is actively being occupied to determine feasibility. The space sounds to have great potential.

I am assuming that your heating needs dominate your utility bills. If so, adding solar pv and/or thermal collectors will definitely offset your gas usage. Since a boiler is already present, a "steam back" solar collection array seems to be a natural winner.
http://solarishot.net/wp-content/upl...ne-Diagram.jpg
A typical DHW system

Your system obviously differs from the above rig. You have a gas powered boiler and multiple heating zones, in addition to DHW. However, the basic 2-tank steamback system could be a proven starting point to modify for your specific home.

No windmills (yet, in town location). I do have 300AH of Edison Batteries but they aren't connected yet.

I threw up some pictures that will show my workspace transformation starting in 2002 and ending around 2004.

It has evolved and I will post updated pictures in a bit.

I'm getting ready to start one more big push that I hope can get me very close to netzero including heating. I think I need an Daikin Altherma like system and another 5KW of PV panels.

Initially I designed the thermal storage to allow me to run at higher boiler temperatures for better boiler efficiency and protect it's iron insides. If I use a heat pump as the source I can maintain a much lower water temperature. I think I will start warming up the floor in august will solar thermal keeping the floor temperature around 75 degrees F. Then as it slowly gets colder start boosting the floor temperature to around 95 degrees F. I think maintaining a slow steady low temperature is my goal.

here is a link to the pictures. The top link my not always work

http://projects.cogs.com/

I will continue to message this site based on questions and comments.

Thanks for listening,

Ben

Since you are considering a Daikin Altherma system, I will use that setup for a comparison here.

The units all run with R-410a refrigerant, which is the current American standard. Unfortunately, it doesn't do so well in high-temperature heating applications, due to its somewhat low critical temperature. Above about 110-120 degrees F, heating performance drops pretty quick the higher your destination temperature is lifted. The units all have been designed to yield a COP of about 4 into a 55 degC destination (heat sink) temperature. If you can live with a 50 - 55 degC heating water temperature, the low-temp line looks pretty attractive.

However, if you need higher heating water temperature (due to radiators, baseboard heaters, etc.), the COP of the Altherma units drops off to below 3 with the additional heating gradient. I didn't look deep into the ratings, but I'm sure those figures are not in frigid outdoor air temps. As outdoor air temps drop close to and below freezing (0 degC), the unit will defrost more often, further cutting into efficiency and raw heat output. Combined with the high-temperature heating gradient, this makes the heat pump not very efficient. Economically, natural gas is a cheaper heat source during frigid weather (more so when high-temp heating).

For the reasons stated above, I would definitely look carefully both at your system design and supplemental heat sources. If you only need high-temp tap water, a modest solar (thermal or PV) source could boost that small percentage of total demand with ease. You could use a low-temp heat pump do supply most of the demand in its efficient operating range. OTOH, if you need more high-temp water to supply space heat, there are trade-offs to be made. There is a big difference in outdoor unit expense between a unit that can provide total capacity on a cold day (with excess capacity the rest of the year) and a unit that (only) provides capacity 90% of the time. The difference in upfront cost could take a decade to pay back in efficiency.

Have you seen the solar tie-in systems for the altherma?

I can I deal with the low temperature water for the 2 offices.

The house is currently on steam radiators. I think I will install very closely spaced 4" or so on the first floor since I have access from the basement. The second floor of the house will probably get the low water Rental Radiators I used in the second office.

I believe I will be able to then heat all 3 buildings off low temperature water. We rarely get more then 15 days a year when it 5 degrees F or lower a year. I'm ok with not having an efficient system on those days. The other attraction to the Altherma system is that they seem to offer a chiller that works off the hot water loop. To tie this whole project back to the subject title. I want to try and get some sort of refrigerator running off my heat-pump.

You can do that with pretty much any system. The feature you are referring to is a desuperheater hx. It is plumbed in directly after the compressor in the refrigerant loop, before the reversing valve. It always sees the hottest temperature gas leaving the compressor, regardless of whether the unit is heating or cooling.

The opposite is not so easy. You cannot just tap into the compressor suction line and cool water with that stream of refrigerant. The lion's share of the cooling capacity is realized as the refrigerant is changing phase from a liquid to a gas, immediately after it squirts through the metering device. The suction end of the cooling coil (evaporator) is opposite the metering device end, so by the time the refrigerant reaches the suction end it has expanded. 99% of the heat has been absorbed at low temperature (latent heat transfer), and the remaining heat (sensible transfer) occurs by the gas changing temperature. Even with low counterflow heat exchange, there isn't much left to be had.

Added to this conundrum is the reversible nature of the heat pump. If the unit you choose doesn't change direction between heating and cooling modes, it is easier to directly rig in a chiller circuit. If the thing changes direction, you would need a dedicated chiller circuit plumbed in that short-circuits the reversing valve. Either way, your chiller is going to rob capacity from the cooling circuit one way or another. Whether or not that matters makes a difference as to your options. Also, the chiller circuit would be a slave to some other heating or cooling demand in the house.

As far as Hot potable water and freezerating go, they are usually a much smaller load to satisfy than the space heating and cooling needs. Other ecorenovators have toyed mercilessly with these comparatively tiny loads, and had resounding success. A run-of-the-mill dehumidifier can be modified to simultaneously make plentiful amounts of cold space and hot water, consuming about 250 to 300 watts while running. Maybe more power than a TV running, but definitely less than a desktop PC running. In comparison, most whole-home a/c units draw at least 2000-2500 watts while running.

I hope I didn't confuse you too much in this post. If so, just read through some previous threads. Many have been where you are now in their own struggles, and it takes a good amount of planning to get what you want out of your system. Superior efficiency is all in the figgerin', so to speak.

Yes, it was those dehumidifier projects that peaked my interest in the site and prompted me to join. I should probably consider a secondary hot water source as an emergency backup.

I will try to start tinkering with one this summer.

There are a few members tinkering with phase change materials. These serve as thermal batteries in the temperature range you choose. On the hot side, calcium chloride and water mixture is perfect for DHW. On the cold side, there are brine solutions and organic materials available. These materials store 4 to 14 times as much heat as ice melting to water (or release heat during freezing), and can drastically change things for the better. They work the same way as your sand bed floor, only they hold more heat per unit volume, and while charging and discharging they stay just about constant temperature. So for say, the same heat capacity as a 100 gallon water tank, you only need like 8 or 10 gallons of PCM material. Charge the PCM with hot or cold when it is economical/available, let the PCM take up the slack.

Here's an article on a solar walk-in freezer:
http://www.pcmproducts.net/files/Sol...e%20System.pdf

The referring page:
solar thermal heat storage and heat recovery programmes

I read through the phase change material (PCM) article. I think I'm going to to set-up a precise measurement/logging system over the summer. Then this winter gather the data to calculate the kWh of storage in my sandbed. I also want to experiment with how low a water temperature I can use.

Oddly enough my battery storage is about the same as the the one in the article.

I wish it stated how much PCM was used. I wonder if my larger quantity of sand makes up for the efficiency loss of using a PCM?

After viewing your link, I am convinced: you have the disease. No doubt about it. I am now thoroughly bewildered. In addition to the genius of Caractacus Potts, you have the work ethic of Willy Wonka as well.

Quotes to support my discovery:

"Caracticus Potts: Mm? Oh. Do you think I'm a lunatic, wasting my time on a lot of silly inventions?
Jemima: But they aren't silly! They're wonderful!
Jeremy: Nobody else can think of them."

"Willy Wonka: [making a mysterious formula] Invention, my dear friends, is 93% perspiration, 6% electricity, 4% evaporation, and 2% butterscotch ripple.
Mrs. Teevee: [as Mr. Wonka drinks the formula] That's 105%!
Sam Beauregarde: Any good?
Willy Wonka: [smacks his lips, then speaks in falsetto] Yes."
http://projects.cogs.com/images/bb-125.jpg
Seeing the garage project, it is clear now that you cannot use the sand slab for a medium or high temperature heat store, since the space is at least partially finished living space. Doing so would turn that area into a sauna above a certain slab temperature. Unfortunately, that certain temperature is probably below your minimum heating supply water temperature. However, that zone will be particularly easy to heat with low temperature supply water.
http://projects.cogs.com/images/bb-103.jpg
That is some really nice looking work! Please feel free to write us an encyclopedia about this project.

Thanks for the feedback:)

The current goals for the sand slab is really to act as a moderator. I want to keep it between 100F-86F degrees during the heating season. So my current quest is for generating water up to 110 degrees during the heating season.

Here is how I'm thinking I will use the sand slab. Charge it during late summer with solar thermal drainback system that could also be used during sunny winter days.
Once the sand slab is charged there will be days it can handle the heating alone and other days will it be charged using some sort of heat-pump.

On the coldest days the sandslab can boost the water temperature with could be a problem with an air source heat-pump.

I have just been doing some calculations to figure out the quantity of btus I can store and looks like I can store 341,100 btus. That I can use for passive heating of the my office or boosting the water temperature of the system or both.
I got the numbers based on these links:
Using Sand to Store Solar Energy | GreenBuildingAdvisor.com
Sand bed storage for solar homes

This is an interesting photo because it happens to be the only piece of polycarbonate I had to cut in the whole curtain wall. I cut it to fit and then I set the table saw to 45 degrees and and cut a chunk but not through the polycarbonate to get a nice fold in the corner.

I don't plan on changing the temperature I currently operate at.

Incidentally that plywood wall is from our previous apartment that I reused.

I will try to get some current pictures posted soon and more of a narrative.