shanafme t1_j81od0d wrote on February 10, 2023 at 11:36 PM

Reply to comment by MarvelAtTheSky in PA Incentives for going to heat pump water heaters by gullyBo1z

Regardless of what this guy says, I installed a HP hot water heater in my basement this past summer and I'm saving big bucks. My previous electric water heater was probably using 30-40% of my monthly electric bill. With the HP, my electric bills have probably halved (even considering recent price hikes). Sure, it will be a few years before I break even, but I think it is worth it, especially with the price of electricity increasing as it has been.

Aggravating_Foot_528 t1_j81q2em wrote on February 10, 2023 at 11:48 PM

Did you have a 220v outlet already?

the_real_xuth t1_j81sd01 wrote on February 11, 2023 at 12:05 AM

> My previous electric water heater

Based on this comment, presumably they did. But even if they didn't, adding a 240V outlet is not very expensive as long as its location has reasonable access to the breaker panel and you have available capacity. If you don't have available capacity then you really want to consider upgrading that in the semi-near future regardless because you will absolutely want it.

Aggravating_Foot_528 t1_j81t9ng wrote on February 11, 2023 at 12:12 AM

Duh. I totally missed that they swapped out electric for electric. My house is gas so whenever I think about adding electric I think about the 220v line.

I have 200 amp service but it's unclear at what point do you need a 2nd box if you concert a lot of gas appliances to electric or add a plug in car.

And as you said I know physical box space makes a difference too.

the_real_xuth t1_j82t846 wrote on February 11, 2023 at 5:13 AM

If you have 200 amp service in your house, the wiring to your house is at least sufficient for household electrical needs for the foreseeable future. However you may want more discrete circuits in your house than your panel currently holds or you might want to wire in a bunch of new circuits to a location far away from your electrical box, and then it is often worth your while to put in a sub-panel. Presumably if you have 200 amp service you likely have a decent sized electrical box. And even once all of the slots are full, you can get away with a few breaker slots being doubled up. But eventually there comes a point where the box is too crowded to safely work in it.

For instance when I moved into my new house, I wanted to set up a small wood and metal workshop in my garage. My garage is on the opposite side of my house from my main electrical panel so it was worth it to me to hire an electrician to install a subpanel in my garage so that I'm only running one large electrical circuit all the way across the house and through a foundation wall rather than a dozen smaller ones.

Similarly when I moved in, I had 100 amp service to my house and the main panel was both small and completely full. 100 amps would cover my immediate needs but I did want more circuits in the main house. So I could have gotten away with installing yet another sub-panel near the main panel. But I had no headroom for doing things that I anticipate will likely happen in the future (switching to a heat pump for heating and hot water, I can't imagine that my next car won't be electric, and likely other unknown uses). Thus I opted to just increase my service line to 200A and replace the original small panel (that likely was installed when the house was built in the 1940s) with a much larger panel.

MarvelAtTheSky t1_j81u4x8 wrote on February 11, 2023 at 12:18 AM

So, your electric bill is lower, but if it is collecting that much heat in your basement enough to overcome its balance point on a consistent enough run rate to save ‘big bucks’, where is the heat energy coming from that gets to the basement for it to extract when it’s 30 degrees outside?

Your floors are providing the heat via your furnace heating the house. If you read my post I’m not giving hard numbers or saying they don’t have a use case, but the movement of heat energy is very complicated, so much so my work is done for the Department of Energy, ASHREA and ACCA and is only accepted when it’s corroborated with three other engineers work. If your loosing that much heat energy from the buildings thermal envelope, your biggest savings are insulating your house, in which case once you would, your heat pump water heater that has a high balance point of close to 50° would end up running almost entirely on its electric element.

shanafme t1_j81wa5z wrote on February 11, 2023 at 12:34 AM

Yes, I went through the process of improving the home’s insulation prior to installing the HP water heater. HP Water heating is using about 50-60 more kWh in winter months than it was in the summer. Also using an air-source HP for general heating.