Finally Installed GE Hybrid Heat Pump Need Advice

1.6 gpm is good. you might have enough warm water left after 27 minutes to recover the water heater to take a shower in another 40 minutes. Not sure what you are using for a storage tank. Make sure it is insulated well. Pipe the cold into the bottom via a bottom tap or dip tube and take the hot out the top to the water heater cold inlet. Turn the pump off and forget the reostat. KISS.

I'll give that a try. Recovery in heat mode is only 8 gallons an hour. In standard mode (eats electricity) it's 23 gallons an hour. I have a total of 50 gallons with the GE unit. With 3 showes back to back I don't think I'll have enough capacity. It would also be nice to have extra capacity if family visits.

We took 3 showers back to back with lots of very hot water. I throttled down the stream of hot water going from the storage tank to the GE Heater. Turn over of the water in both tanks is lessened which keeps any cold water from being mixed into the hot water when we are drawing from both tanks.

To Recap: I have the cold water at the bottom of GE tank going into the cold inlet of the storage tank and then I have a circualtor coming off the hot side of the storage tank (has a dip tube) going into the top of the GE heater. There is a valve that I'm using to restrict the flow of water between the two tanks so the wate going into the GE tank isn't too turbulent and doesn't runover the water in both tanks too quickly. The idea is too use the hot water on the top of both tanks first..

Works great! Thanks for the positive, helpful posts. This thread allowed me to think outloud and get some great advice.

Have you tried running it in heat-pump mode without the storage tank?

markviii wrote:Have you tried running it in heat-pump mode without the storage tank?

We take a total of 3 showers back to back which is a total of 37 minutes of showering or 55 gallons of water. There is basically no recovery in heat pump mode. Just 8 gallons an hour. That is the reason behind the storage tank. I originally plumbed it so the cold water was mixing in with the hot water (tried to keep my current setup that I was using for my stove coils and got lazy) and we had terrible showers. After I went to this new design it works great. I guess I should try it without the storage tank but that would have to wait for a weekend. Both tanks have good insulation and there is no flue to lose heat from so standby loses should be minimal even with the storage tank. Our hot water usage would be the same with or without the storage tank so it shouldn't cost much more to keep the extra gallons ready to go. I insulated all the pipes too that go from the GE unit to the storage unit too. Any lost heat will be recovered back anyway (thank you heat pump)The storage unit is an electric heater that isn't wired. This is great since it has a dip tube and allows the cold water to stay at the bottom of each tank.

traderfjp wrote:To Recap: I have the cold water at the bottom of GE tank going into the cold inlet of the storage tank and then I have a circualtor coming off the hot side of the storage tank (has a dip tube) going into the top of the GE heater. There is a valve that I'm using to restrict the flow of water between the two tanks so the water going into the GE tank isn't too turbulent and doesn't runover the water in both tanks too quickly. The idea is too use the hot water on the top of both tanks first..

Good to hear it is working well! So, are you saying essentially all your hot water now comes from the heat pump? What is the temperature of your cellar this time of year, or the temperature wherever you have the two tanks installed?

Threw 400' of 1" black water pipe in coils on the barn roof today circulating into a 600 gall SS milk tank I picked up at an auction when I was drunk. Last summer it worked perfectly washing horses all day. Just call me Mr Technology. - I'll one up that muleskinner off of RT81 or die in the attempt.

There are some very cool homemade solar hot water heaters. If you live in a warm climate it's almost stupid not to use the sun for heat/hot water. In the East it's a different story since we have so many cloudy and rainy days. We also have to deal with winter snow and all that. That said I heat my 40k gallon pool with 7 solar panels on my house. It's free energy and allows me to extend my season a little longer.

coalnewbie wrote:Threw 400' of 1" black water pipe in coils on the barn roof today circulating into a 600 gall SS milk tank I picked up at an auction when I was drunk. Last summer it worked perfectly washing horses all day. Just call me Mr Technology. - I'll one up that muleskinner off of RT81 or die in the attempt.

I'm glad you got things working OK.

When you calculate how much hot water you use per shower or per minute, don't for get that you are mixing in some cold water. 50 gallons of 120 degree water will make more than 50 gallons of 104 degree water. Also don't forget the cost of running a pump. 12 hours a day will cost $6.50 a month in this state.

The pump pulls 1/2 amp which is about 50-55 watts. If I have this right it comes out to about 1320 watts an day or 1kw and a 3rd of a KW. We pay 18 cents a KW so it would cost me roughly 25 cents a day to run times 30 is about 7.50 a month.

24 hours is not needed in my application. Any suggestions on how to setup a timer?

As long as your insisting on traveling this path

let me suggest that in place of a timed application of energy to storage --- you place a temperature well or simple strap on aqua stat on the output to tap of the storage tank

Wire it to open on temperature rise and set at 120 degrees ( domestic hot water max code set temp) or the max that the GE appliance is set to run

then when ever output drops below the set differential of the signal close on the aqua stat -- your pump will inject energy from the production appliance to storage, and when the pump rests - you get at least some tank stratification

Kind Regards
Sting

How can I guesstimate the overall efficiency of my DHW system? I have a fairly new cold start oil boiler and a 30 gallon Superstore tank that sits about 50 feet from the boiler, with insulated pipes in between. We don't use a lot of hot water, but oil use has been very constant at about 28 gallons per month, which seems high to me. That is almost $100 a month at current oil prices. A friend with a similar system but a larger family says he uses only 10 gallons per month. Interestingly, 28 gallons a month is almost exactly what my brother’s always-hot oil system used when he left it running for six months while the house was empty.

I have been told by several people to install an electric water heater and use it in place of the oil, at least during the non-Winter months. "Your electric bill will not increase by $100", they say, which seems true. Electricity here is 16 cents per kwh, or about $47 per million BTU. If my oil system is only delivers 50 percent overall (71,000 BTU per gallon), oil at $3.35 would likewise be $47 per million BTU.

So it comes down to a question of standby losses in the boiler and piping. Does it seem likely the oil system loses fully half the heat available in the oil it burns?

10 gallons a month for a large family doesn't seem possible unless he has everyone in the house trained to take a 5 minute shower. I was using about 20 gallons a month with 4 adults in the house. However, I had a dedicated oil fired hot water heater. You are keeping a boiler at 160/180 to heat water to about 125. This makes no sense to me. I would go with a heat pump unit and get off oil or better yet natural gas if you have access to it. I haven't gotten my first electric bill yet but I can tell you that my heat pump unit is doing the job. I did bastartize it a bit so your mileage may differ.

traderfjp wrote:You are keeping a boiler at 160/180 to heat water to about 125.

No, my boiler is cold-start, so if there is no call for heat from the Superstore tank the boiler itself can go stone cold. But in a sense you are correct, because during daylight hours there is often enough hot water use that the boiler never cools down completely. Therefore I have more or less continuous standby losses from the boiler and piping, except at night. What I am trying to figure out is, what percentage of my oil bill is going purely to the boiler standby losses.

Standby losses amount to a huge percentage of DHW use.

For example, I have a family of 4. I heat DWH with propane and use propane for the dryer and cooking. In the winter I heat my DHW off a tankless coil from my boiler.

My propane tank is a 100 gallon tank. They can only fill the tank to 80% capacity by code. This is 80 gallons of propane. I have my propane on automatic delivery every 3 months. During the summer, if they are late on delivery I run out of propane. In the winter I use an average of 35 to 40 gallons every 3 months for dryer and cooking. The difference of 40 to 45 gallons is what I use every 3 months for heating hot water.

I am fortunate that we do not take excessively long showers and we have a front loading washing machine that conserves water.

Direct fired dhw heaters are more efficient from a standby loss perspective. Indirect units, you have not only the storage tank losses but all of the piping and the boiler being heated up everytime there is a call for DHW.