Wow- old school.

Growing up we had that, then put in solar hot water with the oil burner as backup/supplement. This was in NY.

 

[QUOTE=gonavy]About the tankless heaters- I've thought about them, but I'm not sure they save for a family-size household- capacity is simply not there for 5gpm @120deg for electric models. They claim it, but I've had 3 installers tell me it just ain't there. For small households they should work great.

Have you put the heater on a timer? shut it off except for a few hours before you use hot water, and wrap the heater in another layer of insulation.

My ideal would be a tankless instant heater at each point of use. Only one run of piping through the house- fewer points of pipe failure, and if one heater goes you still have hot water at the other spots.

QUOTE]

I have a brother-inlaw with a tankless waterheater and he seems to like it but I've also seen him having to run the water in the kitchen for about a min just to get hot water to it. Wonder how much it costs him in the wasted water. Point of use water heaters sound like that would take care of the wasted water but then there is the extra cost of having 3 extra water heaters.Kevin

 

Ok, for those of us who live with slightly lower demands, even electric tankless can work just fine. Check out this spec page:

Tankless water heaters

The "cold" water in Phoenix never gets below 55 degrees or so, and I like about a 95 degree water temp for washing up. I have a 2.1gpm @ 80psi shower head, although actual water pressure is 65-70psi, so figure it only really flows maybe 1.8gpm. The smallest model listed on that page can do 1.5gpm with a 41F rise, which would almost meet my needs. The next one up Says it will do 63F at 1.5 and 48F at 2.0gpm.

If you then skip up to the top model, it's rated for 75F at 2.0gpm, which means if you only wanted a 40F rise, you'd be mixing in enough cold water to get a total flow of 3.5gpm or so. That should just be sufficient for two simultaneous showers on the same hot water feed.

The other alternative would be gas fired ones or even multiple units. One of my co-workers has a large house, so one end of the house with the kids rooms and kitchen stuff is on a large water heater loop. The other end of the house with the master bedroom and one guest room has a separate hot water loop with a tankless heater. I personally would kind of like to have one since I hardly use any hot water at all (maybe 20 gallons a day?) but the 50-gallon, dual element water heater of mine sits there all day long heater water to 120 degrees. It also takes up a bunch of room in my small garage.

It's not really something I'm looking to do right away but I think at some point I'd like to try a tankless water heater. Someone also asked if I've gotten a water heater timer. I have not, but I've experimented with using the circuit breaker to manually turn the water heater on and off. There was almost no benefit to only running the water heater in the morning, and there is certainly a downside to having no hot water at night if I wanted to take a shower. That's really where a tankless water heater would be the best use of energy. They also make real small ones you can put under sinks so you have instant hot water at your sink too. That helps you to save water as well as power.

 

Having your water heater far away from the kitchen would be the same regardless of if you had a tank or tankless water heater. There's two ways to solve that; point of use water heaters (like you mentioned) or a hot water circulation loop. The circulating loop is great for saving water, but it requires power to constantly heat all that circulating water since heat is constantly lost in all the piping. Even with a solar heater included in the loop, that would only offset the water heating for a portion of the day. It then becomes a question of which do you want to conserve more: water or power? A point of use tankless water heater would let you save both, although at an increased up-front cost since you'd be installing water heaters at every major point of use.

I guess the ultimate would be a hybrid where you have a hot water loop with a fully solar heater tank that is set either unregulated or set to achieve some potentially very high temperature like 140 or 160 degrees or whatever peak temp you can reach via solar. Then have the solar heated loop feed all the hot water lines. Sure, it would lose heat through the pipes as it circulates, but even overnight it could probably maintain a water temp well above the standard cold water, thus saving power for the on-demand heaters to only achieve a much lower temperature rise. Come to think of it, hybrid makes everything better, doesn't it?

 

You could also use a plate heat exchanger off the high side of a heat pump,run water thru it and into the waterheater and back, waterheater would then be used only for back up or when heat pump isn't running. I've seen this work and it saves quite abit of energy. Kevin

 

Most geothermal heat pumps use this desuperheater technique to provide free hot H20 from the heat rejection in cooling mode, and can also (pre)heat in heating mode, at cost.

To qualify for the new $300 Federal credit, a geo system MUST have a desuperheater! Why heat up the Earth's crust when you can heat your water instead?

from the energy bill:
Sec. 1333 Credit for certain non-business energy property (page 1351)
One of the highlights of the new bill addresses homeowners, who are granted up to $300 in tax credits for the cost of new Geoexchange systems. To be eligible, the standards that must be met are 14.1 EER & 3.3 COP for closed loop, 16.2 EER and 3.6 COP for open loop and 15 EER and 3.5 COP for DX. However, the system must include a desuperheater or integrated water heating to meet the credit's criteria.

http://www.geoexchange.org/incentives/incentives.htm

An air-air heat pump can do it too- still free hot H20 in the summer, at least. Almost certainly not worth the cost in winter, though.

 

This is an excellent thread. It shows that guys/gals posting here are concerned with the environment.That we also get some wallet benefit, it is only the icing in the cake.

 

Actually, I was thinking I might ask Jason if he could set up a new forum when he is between semesters. One for 'home hyperwatting' or something along that line, so we don't have to squat in the catch-all forum..

Its OT from the point of this site, but very closely related in the larger picture. And many of the same hypermiler philosophies play out similarly in a house too.

 

Ok, so kind of on the subject of energy conservation, I have had my refridgerator plugged in to my Kill-A-Watt for a few days now. I also have a thermometer in the middle of the freezer to monitor temps. I noticed it's doing a defrost cycle right now. Does anyone know how often the average fridge does this? Like once every 12 hours, 24 hours, 3 days, etc? It was drawing a good 600 watts to provide the initial heat to get the defrost cycle started, and then appears that it shuts off and just lets the freezer warm up naturally for a while before it goes back into cooling mode.

So far, the total kw/h consumed seems in line with readings from my previous data recording session (which spanned about 60 hours) but obviously a defrost event would affect the numbers, so like if one experiement had 2 defrost events and the next experiment only had one, I don't think they can be fairly directly compared.

Oh, and for the curious, I previously had the freezer set at "5" out of 10, with 1 being warmest and 10 being coldest and the fridge is set at "6". The 60-hour average with those settings worked out to about 2.18kw/h per day. I'm now 24 hours into having the freezer set to "1", which outside of the defrost cycle appears to have raised the average temp from about -2 to about +7 and it's used 1.90 kw/h in 24 hours.

 

AFIK defrost happens every 24h on a typical fridge/freezer combo.