4 ms·
Speaking specifically of heat pump water heaters - I will absolutely cede that they are more efficient, but holy _crap_ they take forever to recover. My previo
by isbjorn16 8y ago
Speaking specifically of heat pump water heaters - I will absolutely cede that they are more efficient, but holy _crap_ they take forever to recover.
My previous water heater was a 70 gallon conventional electric. It didn't have quite enough hot water to get everyone through showering when we had extended family over, but it recovered reasonably quickly so that we only had ~ 30 minute gaps or so in waiting between the person who felt it get cold first and the next in line. Pretty reasonable.
Ours was about 20 years old and we also wanted a bunch of other plumbing work done, so we decided we may as well bite the bullet and get a new one. We replaced ours with an 80 gallon hybrid (electric + heatpump). We figured the extra 10 gallons would probably actually completely negate the need to wait between showers for those last people, so we were super stoked.
The reality is it exacerbated matters drastically. The refresh rate on our old water heater apparently was almost good enough to keep up with sustained usage between 7 people. The current one runs out of hot water out of 2 and takes well over an hour to even have enough hot water for a single next shower.
I tend to take pretty long showers in the morning - like 20 minutes or so. I use a CPAP and clean my mask, I brush my teeth, I brush my invisaligns (which is why I do my teeth in the shower - it's impossible to scrub invisalign braces and not fling infinite toothpaste flotsam everywhere), and I wash myself (which honestly is the fastest part - I keep my hair next to non existent and just do a body wash from head to toe, rinse, and leave. The point is that the 20 minutes I spend in the shower, with a low flow water reducing showerhead, still means my wife gets to get a cold shower an entire hour later.
However, from what I was told, there are new regulations regarding electric hot water heaters; namely, you can't get over 60 gallon tanks with a conventional hot water heater. Apparently people are getting around this by buying light industrial ones, which don't have this limitation. I wanted to try to cut down on energy usage AND I was keen on the idea of having a heat pump in my garage, transferring the heat in said garage into the water, thus leaving the garage cooler. It's like a really inefficient air conditioner for my garage, but given how hot that gets in the summer and how little I spend time in my woodworking shop, I wanted to leap at the chance to maybe make it a better environment.
All of this is a long winded way of saying it may win on efficiency, and it does have a number of compelling secondary features about it, but it also still suffers from poor refractory performance. If you have one as well - do you notice issues like this? Perhaps the one I got is faulty or just ... not good.
- isbjorn16 8y agoActually, come to think of it - it might just be that it's pretty cold in my garage right now, ~ 40F: maybe it just isn't getting much help from the heat pump and the conventional electric heater isn't doing a great job on its own? I'll have to pay attention into summer when it's like 95 in my garage. Maybe I can presume raging hot showers -for days- at that point :D
- cmurphycode 8y agoThat's definitely part of it. I'm actually surprised it's working in heat pump mode at all. We have a hybrid and it will run pure-resistive if the ambient temperature is below 50. Now, it's in our basement, so even in the winter that's a reasonable cut-off - not sure if you got a specific model for being "outside". Speaking of which, does your model not have a resistive backup? Ours has several modes: - only use heat pump, unless not safe to do so (ambient too cold) - use heat pump normally but fall back to resistive to recover - use resistive only We only have 2 people in the house so we are able to leave it on the first mode, but in the second mode it would, presumably, be the same performance as our old resistive-only heater.
- isbjorn16 8y agoSolid questions - I'm going to take a peek at it tonight. I honestly haven't given it a lot of thought, but literally just this morning my wife went off on a rant about it for a good 15 minutes. It suddenly bubbled up my priority queue pretty quick - and then out of nowhere, this thread on heat pumps and water heaters! Crazy coincidences sometimes.
- ip26 8y agoHave you heard of drainwater heat recovery? One of the side benefits is dramatically improving the recovery rate of your water heater. (Unfortunately it doesn't work well with certain plumbing layouts, and the rising price of copper has reduced the cost effectiveness)
- mrclark411 8y ago