Heat pump H2O water heaters??

[Servicetech]

MN, you make a good point. It's not just Oklahoma socking people with high service fees while keeping the cost of fuel cheap. Service fees for us are a whopping $28/mo, so little incentive to save gas use. Dropping the $336/yr in service fees for the gas meter makes going all electric worth looking at, at which time the heat pump water heater may make sense.

LED/CFL makes sense for us partially due to the lowering of the heat load during the long summer. LED won't beat CFL on payback time unless bulb life is a factor. If bulbs are difficult to access LED pays for itself the 1st time a CFL doesn't need ot be changed out. I personally like LED just for the cool factor.

[AC_Hacker]

Yup, we natural gas user here in Oregon have the same kind of low-use penalization system.

The gas company has even installed automated gas meters to save money by not hiring meter readers.

There are months in the summer, when my gas use is so low, because of my tankless heater, that the "service charge" is larger than my gas cost.

Even though propane is about double the cost, it's getting very close to being cheaper to use because of the burdensome service charges.

I even called the gas company and told them I'd like to suspend my gas during the summer months, but they informed me that there would be a $20/month suspension fee.

-AC

[NiHaoMike]

In some parts of College Station, TX, the electric company has a big ($40/month or so) service charge and a pretty average (11c/kwh) rate. In other words, a complete rip off. The "all utilities paid" apartments are an even bigger rip off, with the premium such that you'll have to be really unreasonable with electricity use (as in leaving a space heater or large window A/C on 24/7 will not do it!) just to break even on cost. Going off grid doesn't really work out for the 4-5 years it takes to graduate from college.

[AC_Hacker]

I came across THIS LINK to a company that makes these things.

There's quite a bit of interesting info here.

-AC

[Servicetech]

Electric Thermal Storage vs. Heat Pump Water Heaters - Home Energy Pros

[AC_Hacker]

Originally Posted by Servicetech

Electric Thermal Storage vs. Heat Pump Water Heaters - Home Energy Pros

Not quite sure what your point is here...

Curious that the article differentiates between

• Units that heat up water during off-peak times so that it can be called upon during times when electricity costs less.
• Units that use heat pumps to heat water with greater efficiency.

They say this as if heat-pump water heaters could not be used during off-peak times... odd.

The article also mentions a project wherein electric [resistance] water heaters will be designed to be as efficient as current heat pump water heaters. Since the resistance heating process already is essentially 100% efficient, there will be no gains to be made there... So it looks like superior insulation will make the difference.

So, if you converted a super-insulated electric water heater to be a heat-pump water heater, and managed it (can you spell Arduino) to run at off-peak times, you'd be a triple winner.

In fact, I believe that Xringer is doing something pretty much like that (maybe minus the super insulation), but he is adding solar energy to the mix. Last I tuned in, he was using his solar panels to power a resistance element, so it could be improved by powering his heat pump with solar volts kicked up to 120AC via an inverter.

Efficiencies do add arithmetically.

BTW, there is a Fuel Comparison Calculator available that will allow you to input fuel values (even Oklahoma Nat Gas) and specific efficiencies, too... so you can double check that your posts are correct before you push the "Submit Reply" button.

And also since this is a get-down-and-dirty DIY Energy Geek forum, making claims about Break-Even becomes a little bit more difficult, since many of our most resourceful members glory in being able to convert discarded (as in trash) HVAC units into fully functioning units that they were never originally designed to be.

HERE is a perfect example of what I am talking about. His neighbor asked him to haul some stuff to the dump since he was going there anyway... And he made a functioning heat pump water heater from that trash. That homemade unit is now saving his parents hundreds of dollars per year.

But you could actually use the Fuel Comparison Calculator to figure Break-Even, for cases that unusual.

Best Regards,

-AC

[jeff5may]

How better could our tax dollars be spent than to compare a kludge of one kind and a kludge of another kind, but not a combination kludge that would obviously leverage the advantages of both?

My big question with regards to the article is this: how can the DOE try to force manufacturers to make resistance electric heat stores that have the same efficiency as a heat pump water heater? Unless they are using a HPWH that has ZERO insulation, a resistance unit would have to be UBERinsulated, like a thermos or better, to stand a chance. Most HPWH's have a 250-300% advantage per watt over straight electric. UNLESS... the DOE allows the heat stores to accept alternative forms of heat (besides electricity) and counts this added heat as free energy...

[Servicetech]

Making homebrew solutions with cheap/free parts certainly affects the break even period. Not to mention some of these projects are just plain cool. I recently replaced my 88k 80% furnace with a 44k 90% that I bought as a "old stock" (2004 that was still new in box) for $250. Sold the old furnace for $175. I figured I'd get my $75 back in one winter, but made the switch mostly because the 88k would blow me out of the house every time it cycled. No way the project woudl have been effective if I would have paid the retail for the heater..

[MN Renovator]

This brings the question, which heat pump water heater has the best insulation? Is there a comparison somewhere? I know they all have their ratings but it seems difficult to track the details down and compare. Especially when insulation is one factor, COP is another factor(of course with the COP being different for every temperature both in the tank and ambient possible).

It seems the Marathon tank with the lifetime warranty appears to have a hefty amount of insulation in its construction but is a resistance heater. That one might be worth it for someone looking to retrofit a tank. Hard to know what to expect versus the ready made units because going either way is going to be expensive as the Marathon tank isn't cheap. ..although I think there are some serious limits to what you can expect from the $20 fiberglass blankets when you want serious energy savings versus just a dent.

I agree with the sentiment that the retrofit is a great way to go if you've got the skill and tools to do it. The COP might not be as good as a ready made unit but the cost will definitely be in a good place.

[AC_Hacker]

Originally Posted by MN Renovator

...The COP might not be as good as a ready made unit but the cost will definitely be in a good place...

Don't be too certain that a homemade heat pump water heater will automatically lower in efficiency.

Our lives are already filled with appliances that were designed to hit a particular price-point, rather than a particular efficiency.

Microwave ovens are a great example. The transformers are a very expensive part of that unit... maybe the most expensive. So the manufacturers build in cheaper transformers to hit the lower price point, and the citizen who buys that microwave oven pays higher energy cost to operate it for the rest of that appliances service life.

I'm not hearing any of our fellow innovators wanting to under-size a heat exchanger because they want to build a cheap project... Nope, it's the other way around, they are willing to spend more money (more often savage a bigger HX from another discarded donor unit) to make a higher efficiency project.

I don't know if you followed any of Brad_C's projects, but he went to extreme lengths to increase efficiency. He had a Brazed Plate HX that was so big he needed a dolly to move it around... all for greater efficiency.

MN Renovator, I think you need to go get a nice brazing torch and a vacuum pump and start having some fun.

Originally Posted by MN Renovator

This brings the question, which heat pump water heater has the best insulation? Is there a comparison somewhere?

You're talking about picking the best from a pool of deficient product choices. I'm afraid that the free market (if there actually is such a thing) doesn't do everything right. There actually are choices that favor efficiencies that might not pencil out in the short term... like one year, as Servicetech seems to favor...

I followed some European energy blogs a few years back, and they have made some substantial progress in tank design. They are working on the idea of a water tank being a 'thermal battery' that can be a storage for heat from various sources, electric resistance, heat pump, solar, biomass, which ever source conditions favor.

Given that Europe pays about 2X+ for energy compared to the US, they have a heavy incentive to come up with some very interesting and innovative units.

Here is a graphic of the kind of thing that is being developed:

MORE...

Here's a similar unit built in the US:

MORE...

Think there might be a difference in insulation??


The really good US tanks have temperature loss rating in degrees per day... the really good European tanks are rated in fractions of a degree per day.

We can study and learn all we can about how this kind of thing is done, and do it ourselves, possibly even better than the European units.

-AC