Tankless water heaters are terrible....

[mongo]

You are neglecting cooking and showering moisture (plus a number of other sources: plants, clothes drying). A very rough estimate for those would be:
Respiration and perspiration: 4.2 lbs of H2O per person per day.
Shower: 0.6 lbs per person per day (5 minute shower)
Cooking: 2 lbs per person per day.
Each of those pounds of water involves 1075 BTU (0.32 kWh) of latent heat.

Not neglecting:

. Thermal resistance should be the dominant factor (depending on ventilation strategy).

The bath/ shower should be vented to the outside, clothes drying definitely so.
I don't know how you get a quart of water a person cooking, unless they always eat pasta and cook on a gas stove. Cooktop should be vented for air quality, so a portion of that should not apply to moisture load. True, plants, pets, dishwasher, and general cleaning add to moisture load.
Going with your numbers, that is 6.8 pounds of water or 7,310 BTU over the day, 304 BTU per hour. Compare this to a 40x40x8 R 26 house with a 30 degree differential to the outdoors at 3,300 BTU per hour. The sensible heat is the larger contributor. Relately, the Chiltrix system supposedly varies unit temp for sensible vs latent control.

One key point is what replaced that tree? If you cut down a tree, put up a parking lot, that carbon is never sequestered again, so it is no different from fossil fuels. Also harvesting energy can be a significant portion of the total. If you are leaving carbon in your ash, you are burning horribly; but ash is not biochar, it gets converted to be plant available very quickly.

Sure, if you don't grow another tree, then you are not recycling and cycle ends back at CO2 vs wood. I'm not worried about the ash, you had mentioned returning it to the forest. My trees get replaced by trees, but wood is not our main heat source (to be honest, the fireplace loses more that it supplies)

 

[Topher]

I don't know how you get a quart of water a person cooking

Not my number, it came from IIRC DoE or possibly ASHRAE.

Thank you kindly.

 

[Alphacrux]

Yes, they are all hybrid heat pumps since they have electrical resistance heating as backup. In the discussion here, Rheem seems to be well recommended.
GE did make a heat pump hot water heater but apparently stopped production due to lots of problems. I didn't know about these problems and got a good price (~$1000) on one as they were selling out the last of the inventory. I've installed it and it has been working well with no problems for 1.5 years... I'm keeping my fingers crossed. I've installed it to provide hot water to a detached garage apartment. It's located in the garage downstairs from the apartment which is good since it does make noise. The garage is unheated but doesn't get below freezing so the heat pump apparently works well.

Love my Rheem heat pump water heater. Installed in the garage and it turned my previously hot and muggy garage into a cool and refreshing workplace during the hot texas summer. And it still works adequately I’m the mild winter.

Next house will have an energy efficient recirculator pump with insulated hot water lines.

Did major energy efficient remodel 2 years ago. Turned attic into conditioned space with spray foam at the rafters, heat pump hot water heater, carrier green speed heat pumps (not enough land for geothermal), insulated garage doors, 9 kw solar.

 

[mspohr]

There are specific accuracy standards that your Envoy meter probably doesn't meet. At my old job we had to weigh UF6 cylinders to verify contents. We had a 'WOHWA' gyroscopic scale that was extremely accurate and Load Cells that were much less accurate but met the QL1 standards so we always had to use the less accurate scales for quality control.

The Envoy meter is on the list of CaPUC approved meters which they told me to follow but they only accept plug in old school meters from the list.

 

[Joel Weber]

I'm looking at using that in my barn (radiant floor and DHW). Might also loop it to a swim spa (with heat exchanger). Interested in any data you dig up.

I'm not aware of any data about the Chiltrix products other than what's on their website; I suspect for the CX34 they're very much in the early adopter stage at this point.

If you do go with a Chiltrix CX34 and want maximum reliability if there do turn out to be early adopter bugs, you might want to see if you can set up the control systems that turn on the backup electric resistance heating elements in the DHW and radiant floor buffer tanks so that they can come on independent of the CX34's control system; I suspect this just requires getting tanks that have space for an extra temperature sensor, and then setting the target temperature for the resistance heaters to something like 2F or 5F cooler than the CX34 target temperature.

Do you have a preexisting floor loop in the barn? My impression is that installing PEX tubing in a floor when the floor is being installed is the least expensive approach to radiant floor heating, and retrofitting may not be cheap; and In memory of Dr. Bob Cupper – Marco.org is enthusiastic about radiant floor heating whereas Radiant vs. Mini-Split isn't so enthusiastic.

If your barn is one big room, and if you want an electric heat pump to heat it but aren't totally committed to radiant floor heating, a Mitsubishi Mr. Slim or a similar mini-split from Fujitsu might well turn out to be substantially cheaper than a Chiltrix with radiant floor heating, but then there's also the question of whether the options to connect to the hot water heater and swim spa are worth something. (And a Chiltrix with a fan coil unit might be cheaper than a Chiltrix with radiant floor heat, too.)

And if you just need to heat and cool one room and don't need a whole lot of capacity, the Chiltrix folks also make a hotel style air conditioner described at PTAC Hotel Air Conditioner | High Efficiency DC Inverter PTAC / PTHP

It appears to me that the major advantages of a Chiltrix heat pump over a more common mini-split are in the humidity control in air conditioning mode, and in the overall system cost if you divide it into many zones for many rooms (Chiltrix has a more expensive outdoor unit than the common mini-splits for comparable capacity, but the Chiltrix indoor units are cheaper).

How much domestic hot water do you use in the barn? Is it enough that having a hot water tank instead of a tankless heater makes sense?

 

[leonoro]

I need more ideas. Anyone help me ?

 

[Big Earl]

I need more ideas. Anyone help me ?

More ideas about what? The last post in this over a year ago.

 

[nwdiver]

Tankless water heaters are good because it consumes less electric power, needs a very small place to set up, easy to run and maintenance, etc.

2/3rds of that is 100% wrong. They use ~3x more energy than a heat pump water heater, require a MASSIVE amount of power and are far more prone to scale buildup than heat pump water heaters. For heating water you can't beat a heat pump unless you physically don't have room for a tank.

Rheem Heat pump water heater Uses ~70% less energy than tankless. It's like adding ~2kW of solar PV to your home for the price of <1kW.

AND.... you can't use tankless for energy storage. I've been running mostly off-grid for >3 months just to get the feel for what's needed. Having a tank to heat helps A LOT with storing excess solar energy.

 

[Sawyer8888]

Rheem Heat pump water heater Uses ~70% less energy than tankless. It's like adding ~2kW of solar PV to your home for the price of <1kW.

Our 80-gallon Rheem heat pump water heater was installed over 3 years and the amount of energy consumed is extremely low. One recent month, our entire electric bill was only $50 (wasn't charging the car much at home). We're completely on the city grid, so no alternative power.

Cooling the garage is a nice bonus when the heat pump is running.

 

[brkaus]

Looks like marketing a referral site to me.

 

[WATTS-UP]

First of all NEVER, NEVER purchase an electric tankless water heater if your thinking about efficiency, go with natural gas. Now if you do not have natural gas then yes the electric tankless hot water heater is better then a boiler that maintains 80gal @ 105 or 110 degrees. One of the best ones I came across is someone in NJ purchase a 10KW solar system so that he could get FREE domestic hot water. They had an 80gal Rheem electric water heater.

On the efficiency scale solar hot water is the most efficient when you have 3 or 4 girls (teenagers) in the house. It may cost you $4,000.00 to $5,000.00 to install a solar hot water heater that will last 30 + years. On average you'll save about $15,000.00 over the file span of the system. Yes, you will have some maintenance costs over the the 30 years.

 

[ohmman]

mod note: removed spam, some posts may have been removed along with it.

 

[iPlug]

Joined this site in recent weeks. Lots of good stuff in this environmental section.

We've had a 65 gallon Rheem hybrid heat pump water heater for about 2 years now and as with Sawyer8888, no issues and it has been very efficient. Family of 4 here, 2550 sq^2 house. Heated water patterns: two showers a day per person, lots of dishwasher and laundry use with two boys, and sink use. We use about 1500 kWh annually.

Wanted to dispel a couple myths suggested earlier in this thread:

1) Poor recovery time: that would be true if heat pump water heaters were not "hybrid", but they all are and come with resistive heating. While "heat pump" only mode is the most efficient and one should probably set this mode as standard, you can chose hybrid modes "energy saver" or "high demand" for additional guests, even force 100% resistive only "electric" mode.

2) Heat pumps can't handle guests situations: this is tied to above, switch to a hybrid mode in this situation and set the heating temperature higher and one should have no problem. We have guests for several weeks a year, usually two additional persons and no problem leaving the unit on "heat pump" only mode with a higher temp setting. Last year we had a total of 11 guests for 24-36 hours resulting in numerous showers; we switched to "energy" saver mode, upped the temperature, and never ran out of hot water.

It's true that heat pump (hybrid) water heaters can not generate heat as fast as tankless heaters, but that is not an issue here or for most households. Sizing the water heater is important. In our case, replacing a 50 gallon NG unit with an upsized 65 gallon one gave us additional buffer room. Rheem makes 50, 65, and 80 gallon units.

 

[nwdiver]

Cabnnot agree with you. As for me, tankless water heater is great, but it requires alot of careful thought to install and maintain it properly. You should do a lot of rerearch before buying a tankless unit. Talk to your plumber, read reviews. From my own experience, I recommend tankless. I actually recommend a solar water heater, then tankless, then tank. If you need some recommendations on models/brands, check out waterfilteriq.com

Did you read past the title? That's essentially what I'm recommending. A heat pump water heater IS a 'solar water heater'. It's just ~80% less expensive and more reliable.

I do like how this thread resurfaces every few months. Demand fees are becoming more common and they typically run >$7/kW. A tankless water heater will almost certainly create your new peak demand so it could easily cost you >$70/mo just in demand fees alone. Ditch tankless before it's too late

 

[Oldschool496]

Mine is gas heated

Mine is gas operated as well, works like a charm. Electric ones are not good. If I was going to do electric Id go back to tank electric water heater. Thats why I changed to Gas tankless.

 

[phigment]

We've had a 65 gallon Rheem hybrid heat pump water heater...

Just installed the same one about a month ago. Love it so far. 4 person family and there have been no issues with running out of water. Set to heat pump only mode and scheduled to heat at night when we have low pricing. Using about 2kWh/day to heat the water. I'm curious how this will work come the heating season when the water temperature drops (Ontario).

 

[iPlug]

Just installed the same one about a month ago. Love it so far. 4 person family and there have been no issues with running out of water. Set to heat pump only mode and scheduled to heat at night when we have low pricing. Using about 2kWh/day to heat the water. I'm curious how this will work come the heating season when the water temperature drops (Ontario).

Our water heater is in the garage. We also use about 2 kWh a day during the summer months and about 5 kWh a day during the winter months, although this is also usually when we have guests.

I suspect you will need a good bit more energy in the winter given your climate. Our water heater is in the garage which is not actively heated and has a couple of vented openings to the outside.

Certainly the water input would be colder in the winter, but depending on placement location ambient air temperature is also important.

Where is your water heater located?

 

[abasile]

We have a standard natural gas water heater that's in a small cabinet on the outside of the house, vented to the outdoors where winter temperatures normally drop below freezing at night. (Even in June and September, we sometimes get pretty chilly at night.)

We also have a gas tankless water heater in a small rental property. The water heater is underneath the house in a "buildup" area that's essentially a tall crawlspace. A standard tank heater wouldn't fit there and still vent properly, so we had to go with tankless (about 12 years ago).

Has anyone tried using a heat pump water heater in such a location? At our home, the issue would be whether the cold intake air would pose a problem. At the rental, the form factor (height) might still be a problem. Thanks for the thoughts.

 

[phigment]

Our water heater is in the garage. We also use about 2 kWh a day during the summer months and about 5 kWh a day during the winter months, although this is also usually when we have guests.

I suspect you will need a good bit more energy in the winter given your climate. Our water heater is in the garage which is not actively heated and has a couple of vented openings to the outside.

Certainly the water input would be colder in the winter, but depending on placement location ambient air temperature is also important.

Where is your water heater located?

The water heater is in the basement right beside the "furnace". It usually gets pretty warm down there when the furnace runs, so the water heating should be pretty efficient. Mind you the air heater will just have to work that extra bit harder. At the same time as installing the ASHP water heater, we ditched the last bit of natural gas coming in to the house and installed a Mitsubishi Zuba ASHP central heater. Can't wait to see how this performs in the winter.

 

[iPlug]

We have a standard natural gas water heater that's in a small cabinet on the outside of the house, vented to the outdoors where winter temperatures normally drop below freezing at night. (Even in June and September, we sometimes get pretty chilly at night.)

We also have a gas tankless water heater in a small rental property. The water heater is underneath the house in a "buildup" area that's essentially a tall crawlspace. A standard tank heater wouldn't fit there and still vent properly, so we had to go with tankless (about 12 years ago).

Has anyone tried using a heat pump water heater in such a location? At our home, the issue would be whether the cold intake air would pose a problem. At the rental, the form factor (height) might still be a problem. Thanks for the thoughts.

Since there are no combustion products, no venting to the outside is required nor often desired with heat pump water heaters. In a hot room, like a garage in the summer, it is nice to have the cold air output to cool the space.

In the winter the problem is more challenging for livable spaces. A cold garage becomes colder, but that’s ok since no one lives in that space. Venting does not help, since porting out the cold air requires the same volume to ingress to the air intake from the path of least resistance outside the room. This ultimately means pulling cold air inside the space from outside the home.

Certainly if the air in the space it occupies is very cold, the heat pump runs least efficiently (ambient operating range 37-145° F) and if cold enough only works in resistive mode.

In terms of physical space occupied by the water heater, the smallest 50G is 61" tall x 22-1/4" wide and the largest 80G is 74" tall x 24-1/4" wide.

The water heater is in the basement right beside the "furnace". It usually gets pretty warm down there when the furnace runs, so the water heating should be pretty efficient. Mind you the air heater will just have to work that extra bit harder. At the same time as installing the ASHP water heater, we ditched the last bit of natural gas coming in to the house and installed a Mitsubishi Zuba ASHP central heater. Can't wait to see how this performs in the winter.

Piggy backing off the ASHP central heater and looks like winter temp low averages 13ºF (-10 to -11ºC) in Waterloo, Ontario. That’s some challenging ASHP “terrain”. If you can pull that off in your climate, that’s fantastic.

Supposing in the basement, an ASHP gets a bit of ground source heat sink benefit– nice.

Yes, please check back in when you have winter numbers!