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Which is more efficient

Posted by Energywise.ks (My Page) on
Wed, Jan 8, 14 at 19:49

I have a heat pump water heater and ultra low flow plumbing fixtures. To get a comfortable shower temp I have the hpwh- set at 135. It still could be warmer for my taste but the faucets are already really hot. The distance of pipe is close to the same and I am pretty sure it is the way shower head distributes the water. If I installed a point of use electric water heater for the showers and turned the hpwh- down to 100 would I use less electricity?

The setup would be hpwh- 100 to house and POUWH- 135 to showers as a booster off the 100 degree hot water line. I am all electric and max flow of shower heads are 1.5 gal with flow control to reduce when soaping up.

I don't mind upgrading but don't want to increase electric usage. The goal is to reduce as much as possible. The rest of the house only needs warm water. We use a HE washer on cold and the dishwasher has its own heater.

This post was edited by Energywise.ks on Thu, Jan 9, 14 at 21:20


Follow-Up Postings:

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RE: Which is more efficient

"It still could be warmer for my taste but the faucets are already really hot."
If i follow you,opening the shower head up or replacing it will cure the complaint at far less cost and save operating expense. Most "water saver" heads only have a plastic washer with a tiny hole. Remove the washer and drill hole a little larger and you are in business.


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RE: Which is more efficient

Unfortunately my goal is less water and less electricity. Most low flow heads will feel cooler by the way they ariate the water. I could go with a higher flow but I have our water usage where I want it. Less than 1 unit per month.


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RE: Which is more efficient

"Unfortunatly" it's not possible to have your cake and eat it to. Your origional question was "which is more efficient".
Now you want to know how to use less water AND electricty. And you didn't even atempt to explain what you meant by "the faucets are already really hot."
Are you trying to yank a chain or just having trouble expressing yourself?


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RE: Which is more efficient

Taking a shower with 135 degree water would burn your skin.

Are you losing a lot of heat in the pipe run (is it real cold where you live?) or maybe there's a tempering device on the hot water system that's limiting the temperature? The spray pattern doesn't change the water's temperature.

Check the water temp with an instant read thermometer, I'll guess it's at 120 degress or less. Are your hot water pipes accessible? Are they insulated?

Setting a hot water heater to less than 120 degress is a bad idea, the result can be dangerous bacterial growth that can lead to many medical problems. Leave it at 130 or higher.


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RE: Which is more efficient

I didn't have a thermometer to get exact temps from the shower and sinks but the sinks are hot enough that you can not hold your hand under it with out tempering it with some cold. The shower is warm but not hot, this is common with some low flow heads that use mechanism to make the low flow seem like there is more volume. Here is a link. http://m.deltafaucet.com/smart-solutions/h2okinetic-showers.html

It is a new construction home with pex - pipes not insulated but ran between the basement and 1st floor. Water heater is located in the finished basement just below the bathroom up stairs so the length of pipe is not that long. Sounds like the most cost effective is to try to insulate the pipe or change the shower head. I really like the shower heads spray pattern and low water usage. It also matches all of the other delta fixtures. So I will start looking at alternatives.

My apologies for asking such a trivial question and understand now that setting the heat pump water below 120 is likely not possible and not advised as it should be hot enough to kill bacteria.

I just thought if I kept the tank at the lowest setting of 120 and got a point of use to boost the temp it would use less power than increasing the tank to meet my desire for a hotter shower. Not a huge cost as I can wire it and my friend is a plumber and would plumb it in for a case of beer. The cost of the units I was looking at were around 150. The shower gets used 4 times per day at 15 min each at 1.5 gallon per minute. There might be a cheaper point of use that could increase water temp by 20 degrees with a 1.5 gpm. Flow rate.

I just posted the question to see if anyone else had tried a similar setup or for fun wanted to help crunch the numbers to determine which way would use more electricity. Thanks in advance for all the advice and feedback.

This post was edited by Energywise.ks on Thu, Jan 9, 14 at 21:19


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RE: Which is more efficient

"Unfortunatly" it's not possible to have your cake and eat it to. Your origional question was "which is more efficient".
Now you want to know how to use less water AND electricty. And you didn't even atempt to explain what you meant by "the faucets are already really hot."
Are you trying to yank a chain or just having trouble expressing yourself?

Klem1,

I appreciate your attempt to help and although your suggestion is the most cost effective solution. And makes sense it doesn't answer the original question of which of the two setups I described is most efficient. And I should clarify that by efficiency I am referring to both water and electricity.

I can have my cake and eat too if I choose to spend more money on it; which I have not determined if it is worth while. Which brings us back to why I posted the question.

I am not dismissing your suggestions that a different shower head may be the best solution. Only trying to gather more information on all possibilities before deciding on the way I want to proceed. Thank you again for your responses.


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RE: Which is more efficient

I'll bet there's a so-called "anti-scald" setting in the shower valve that's mixing cold water with the hot. I had the same problem when a new, one-arm shower valve was installed as part of a bathroom remodel.

Mine was fixed by taking off the face place and adjusting the setting to allow more hot and less cold in the mix. If it's new construction, call the builder or the plumber (depending upon which one you deal with) to have someone come to make the adjustment. I'll bet that'll solve the problem.

Whether you need a point of use boost will depend upon the capacity of your water heater vs how much hot water is used and when. Electric water heaters typically have very slow recovery (the time needed to make cold water hot), you haven't said how large your unit is.

Good luck.


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RE: Which is more efficient

Thanks snidely!

It is a GE 50 gallon heatpump water heater. I will check on the anti scald settings you describe and I also found a different low flow shower head that is non-aerating. Won't match the other fixtures but it's an option.

Niagara's Earth® Showerhead saves money by using up to 75% less water than traditional "low-flow" showerheads typically found on the market. While the Earth® Showerhead ensures drastic water usage reductions, the patented pressure compensating technology still guarantees a powerful, consistent flow rate regardless of available water pressure. The showerhead features a 9-jet adjustable turbo massage that easily rotates from a gentle needle spray to a forceful jet. As the stream is non-aerated, the showerhead experiences less temperature -- loss translating to maximum energy savings.


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RE: Which is more efficient

I found this which I think is for my delta Dryden series shower faucet with temperature and flow control.

http://www.ehow.com/how_7887416_adjust-delta-antiscald-shower-valve.html#page=5

I will try to adjust it tomorrow and will be thrilled if this works.


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RE: Which is more efficient

Snidely,

I can't believe I survived 35 years on this planet without knowing about the anti-scald adjustment! Learn something new everyday. Worked perfectly was able to set the heat-pump water heater at 122 which was the minimum temp recommended to keep legionnaires disease at bay. And still I was finally able to take a wonderfully hot shower!

Side benefit is that it takes far less time to get to temp before jumping in and it is hot enough to taper it down with the flow control without getting cold. So we will be using less water! Thank you.

This post was edited by Energywise.ks on Fri, Jan 10, 14 at 15:14


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RE: Which is more efficient

Not all your 35 years were in the dark! I think they've only been required in the last 15 years or so, or so my Googling suggests. It may be that the factory setting is intentionally low for safety/liability reasons and they may often need to be turned up when installed. Or so my plumber said. And that step is frequently forgotten.

I'm glad it worked out for you, happy showering!


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