H2O Heaters - Insulation Matters

[Madcodger]

I've noticed that every night, in the wee hours of the morning, our Bradford White heat pump water heater (recommended and installed by our plumber as we built the place this past summer) comes on for an hour or two, to keep the water at about 125F. As shown it uses only about 350 -400 watts to do that, which isn't much given the task. BUT, I do wish it had more insulation to just retain that heat. That's probably something to consider as one selects a heat pump water heater. We'll try adding an insulating jacket (cutting it to not block air flow of course) but I suspect much further loss is not preventable on this unit. Anyway, food for thought if you're shopping for one, and would be interesting to see standby losses from others here. I'm very happy with the unit, except for these standby losses. We're using only about 2.3kwh/day for water heating, but still, every watt counts.

 

[TechRider]

Do you have all the hot water lines insulated as well? That would probably get you a bigger bag for your buck at this point. I had a hot water re-circ system running for a while. While it was nice to have nearly instant hot water at the far ends of the house, it ended up costing a ton with me heating my basement with the hot water lines. (PEX with no insulation.) I've shut off the pump but I still think I get a little convection from the "hot-links" still being inline at the ends. (They connect the hot to the cold and allow re-circulation without a dedicated line.)

 

[740GLE]

Do you have all the hot water lines insulated as well? That would probably get you a bigger bag for your buck at this point. I had a hot water re-circ system running for a while. While it was nice to have nearly instant hot water at the far ends of the house, it ended up costing a ton with me heating my basement with the hot water lines. (PEX with no insulation.) I've shut off the pump but I still think I get a little convection from the "hot-links" still being inline at the ends. (They connect the hot to the cold and allow re-circulation without a dedicated line.)

I have a “hot link” in stalled on our heater with no pump, it does flow a little heat up to the kitchen which is over an unheated garage (50f in the dead of winter). It’s most noticeable when the heat pump is on and water is expanding, it has a little bit of heat syphoning when not heated. All in all, I’d wager its cots me an extra 0.50/month.

My biggest concern is the heat pump water heater cools our basement down to 55f in fall before we fire up the wood boiler for full house heat. I’m sure that hot water heater struggles to get heat out of 55f basement and cycles a bit more but it does.

 

[Madcodger]

Do you have all the hot water lines insulated as well?

I don't, but we don't have a recirculating pump, so the pipes don't appear to be part of the loss of heat from the tank. Water is plenty hot at points of use.

I think this is more of a design issue, as yesterday I wrapped the tank with one of those cheap insulating blankets one can buy at a big box store (did not block the air flow) and that delayed the typical overnight "on" cycle by about 2-3 hours and the heater appears to have been on for less time than in the past. I'll need a few more days to see if this improvement is real. While wrapping the tank I also noticed that the Temp/pressure relief valve was warm and radiating heat, ore than I've noticed from other heaters I've owned in the past (not dangerously hot - just warmer than I've noticed from others). I can't really cover that as it would interfere with its function, but that's definitely acting as a heat sink.

Bottom line: H2O tank design seems to vary in terms of how well insulated a tank is, and how that allows it to lose heat. I'm not unhappy with this tank overall as it still says us a lot of electricity compared to a traditional electric water heater. But I do wish it lost less heat. It's not the brand I would have selected and I bought it mostly to keep our plumber happy and on schedule as he plumbed the entire new building, but I don't think he (or most plumbers) think much about energy costs when they select a product. My bad for delegating that decision. Such is life.

 

[Bluedog225]

Extra insulation is the easiest thing in the world. Is that an option for you?

 

[Zwy]

I've noticed on Energy Saver mode the Richmond heat pump water heater will cut back slightly on maintaining water temp in the wee hours of the morning. You might look into that. One can also set a schedule for the unit to run with varying temps.

As for tank heat loss, it helps keep my basement warmer in the winter. I did insulate the outlet piping as well as the inlet piping with a U shaped inlet line to prevent heat loss to the inlet piping.

 

[Madcodger]

Extra insulation is the easiest thing in the world. Is that an option for you?

The insulation blanket I added seems to help. Looks like it made it overnight last night from just past 10PM when it last ran, until at least a little past 8:00 as I write this, without coming on (first time that has happened). But this post was more about the need to pay attention to water heater insulation even on heat pump types, than trying to solve a problem. I let our plumber pick the appliance because I was making 100 other decisions at that point of the build ajd it was easier to just delegate it. But I wish I hadn't. It's not a big deal, but these little things add up in an off grid home.

 

[Bluedog225]

I get it. I suspect the manufacturers of these things have some aesthetic and design limitations on how big, therefore how insulated, they can make them.

Bigger boxes, larger storage space for all their units, fitting through doors, etc. The market for super super insulated stuff maybe too small for them to mess with.

 

[Johneb]

We have a recirculating pump on our water heater. Now that we have hot water at the tap without wasting 1/2-3/4 of a gallon of water each time we use it the DW isn’t going to let me turn it off. I am working on how to set the timer so it’s off in the night. I already have the water heater itself on a timer so it shuts off at 9pm and back on at 5am. Working well for us.

 

[Zwy]

Water heater is my house is directly below the bathroom downstairs and the kitchen sink maybe has 10 feet of run. No need to waste water to get hot water.

 

[Johneb]

We apparently have two separate hot water runs in our house. One towards the kitchen and one toward the back bathroom. Both without the circulation pump take the same amount of water to get hot.

 

[Madcodger]

Happy to report that for the second night in a row, the water heater did not come on late at night after adding the insulating blanket. Looks to be saving 200-300 watts per day but it's a bit early to tell for sure.

 

[Daddy Tanuki]

Happy to report that for the second night in a row, the water heater did not come on late at night after adding the insulating blanket. Looks to be saving 200-300 watts per day but it's a bit early to tell for sure.

How long do you think ROI on parts is if you were paying for power?

 

[Madcodger]

How long do you think ROI on parts is if you were paying for power?

357 days, 2.47 hours. But that's just a guess.

 

[Daddy Tanuki]

357 days, 2.47 hours. But that's just a guess.

one year for something I am guessing under 100 USD and an hour or two of labor.... sounds like it was worth it to me. I mean its insulation inside the house so its not likely to go bad.

 

[Bluedog225]

one year for something I am guessing under 100 USD and an hour or two of labor.... sounds like it was worth it to me. I mean its insulation inside the house so its not likely to go bad.

I bet it was more like $30. If regular fiberglass.

 

[Daddy Tanuki]

I bet it was more like $30. If regular fiberglass.

yeah either way long term i think it was worth the cost and effort. its always easier to save power than to generate it.

 

[Madcodger]

I bet it was more like $30. If regular fiberglass.

And it was just sitting in its original package on a shelf in the garage. So, hey, those count as free.