Upgrading failed 50 gal WH - Hybrid, Mixing valves, boosters, etc.

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oneskinnydave

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Hey All,

Been perusing this awesome forum for a few days - super helpful info already gathered but wanted to see if anyone had any suggestions. We moved into a house about 4 years ago that had 2 aging WH (electric) - shocker both of them died within a month of us moving in! We were pretty broke and just put in a decent AO Smith 50 Gal unit....I was tempted with heat pump heaters then but my plumber highly recommended not getting one - parts weren't readily available and the ones for sale weren't very reliable (then).

Last week or so my new heater failed - had a bit of condensation build-up that led to a thermostat going up in smoke and notice the tank starting to fail - AO smith luckily is giving me credit to replace the unit which is awesome. Problem is we have had 2 more kids since then, and we're finding out 50gal electric WH is not great with a 6 person household :)

We do stagger showers, etc - and we can manage OK with lukewarm showers every now and then, but I have a feeling the tank failed because of constant drawing from our well water which is ~60 degrees.

Now I'm looking into the upgrade part - and literally within the last week prices have shot up on ALL heat pump models (80 gal Rheem was ~$1500 around us, now $2000) - AND we lost the $500 utility rebate....as I've been looking for a new unit of course. I was leaning towards Rheem only because it was cheaper, but now the AO Smith and Rheem are the same prices, I think I'd go with AO just for warranty/parts, I can work with a local supply company for repair/parts easily.

I was always thinking of getting 80 gal because of our household size...but I was wondering though if people had thoughts on another 50 gal tank + mixing valve (run it high, then mix down to 120) - or a 50gal + booster electric tankless heaters? Are both of those solutions gimmicky? I think we could do a 66-gallon hybrid but the pricing is so close to the 80 I'd just get an 80, but the 66 gal AO Smith info seems to put out about what we'd need for back to back showers/tub sizes and recovery times.

My plumber is pretty old school, recommends the cheapest tanks and let it run till it dies (hopefully under warranty) and get a new one. He did also recommend an 80 gal light commercial which is also on the table, but I do love the idea of saving electrical costs with a hybrid (we're all electric, no option for gas/propane here) so every little bit helps.
 

Reach4

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Failure usually means leak. If no leak, replacing an element or thermostat will usually fix it. Go for the "low density" elements.

If you have basement space the busy shower, you want to consider a drain water heat recovery unit. Dana has made some great posts on that, and here is one: https://terrylove.com/forums/index.php?threads/purchase-advice-tankless-or-tank.77391/#post-565836

Power-Pipe%20US%20Basement%20Image%20of%20Installation%202013%20FV-main.jpg
 

Phog

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The thermostatic mixing valve will make a 50 gallon tank perform like a 60 gallon tank. You do get some apparent capacity increase but it's not going to double your shower time or anything like that.

As an alternative you could get two 40 gallon tanks pretty cheap from the big box home center & and plumb them in series (outlet of first tank goes into inlet of the second tank). Downside to this is you have to have 2 electric circuits, but it sounds like you're ok with that. You'll also get faster recovery time when compared with a single 80 gallon tank.

The drain pipe heat exchanger like Reach4 shows above is a great option if you have an accessible place to install it. It will give you a bigger apparent capacity boost than the mixing valve would, and will be of energy efficiency benefit irrespective of what type of water heater you get. (Note that it only helps get more shower time out of a tank of hot water -- it doesn't help at all with baths.)

Electric tankless heaters are almost always a bad option.
 

jadnashua

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Depending on how far away the WH are from your showers, you might have to run the water for up to a couple of minutes to get hot...that means, you'll have thrown up to 4-5 gallons of what was hot water out of the tank, and filled it with your super cold water. So, adding a hot water recirculation system would mean that the delay is a few seconds, and you'd not be wasting that water down the drain. Now, on a well, that isn't as big a deal as you're not paying a utility for it, but it still means you're paying to pump it out of the ground. There are lots of retrofit recirculation systems and when used on demand or with a timer and you can insulate at least some of the pipes, they can actually save some money. And, during a drought, not drawing any more water than you really need helps everyone around you on a well, too.
 

oneskinnydave

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Ah interesting, had though of some of these ideas for sure. I think we had our previous water tanks in series, but it was a 75 + 50 gallon setup...which come to think of it meant it may have been parallel?

We did have the house replumbed had polybutylene piping throughout, I’m not sure the access to the shower/drain would be feasible because of the location of the waste plumbing and the WH - but I’ll take a look!

I didn’t think the electronic tankless booster will be the greatest idea, just didn’t know if it would help out when the WH is getting close to overdrawn....I don’t see many people using them or videos of folks using them, that’s probably why :)

I’ll also look into a recirculation setup, we do have a wacky plumbing diagram, not terrible but it’s a little all over the place because of previous construction.

Appreciate the feedback for sure - also, so is the general consensus to stay away from heat pump-based water heaters? The dead simplicity of a basic electric heater has been great for me to fix and repair, I was just thinking about the overall energy usage. My “failure” really was just the thermostat burning up, so that was an easy fix - but has been rusting at the bottom which is why I think they replaced it under warranty, so I’ll take it! I have another week or two to figure out what I want to do before the warranty RMA is up.
 

Phog

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Appreciate the feedback for sure - also, so is the general consensus to stay away from heat pump-based water heaters?

Heat pump "hybrid" tank water heaters are pretty good these days -- or at least we don't get negative feedback about them on these message boards. And it seems like we would, there are a bunch of professional plumbers lurking around here.

Heat pump tanks used to be a novelty 5-10 years ago, but they are fairly common now & seem to be crossing into the realm of Tried & True. My next tank will be one. (Keep in mind I'm not a pro).

Given the high humidity in DC, it would be an especially good choice for you. The heat pump dehumidifies the air & extracts heat from the condensation. So it even helps out your AC system in the summer.
 

WorthFlorida

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Just to throw in my two cents, a standard electric water heater regardless of size all use the same 4500 watt heating elements. There are 5500 watt elements that can be substituted and it will give you a faster recovery rate provided your electric circuit can handle the load. Going to a 80 gallon will not solve the problem much because now you have 30 gallons of additional water to get up to temperature and that takes time.

The heat pump units also will not give you more heated water. When the demand goes up its elements kick in just like a standard heater. HP saves money to heat and maintain the temperature, not an increase in demand.

Look at the Rheem site and they have a small water heater (similar to a point of use) you add at the top of the water heater in-line with the hot water. This will give you at least warm water in high demand use. Might be worth looking into it.

As stated above, the easiest and lowest cost way to go is a 50 or 60 gallon tank with a tempering valve installed. You set the water temp to 140 degrees and adjust the tempering valve that mixes cold water to bring the temperature down to about 120 degrees.

Going tankless may seem to fit the issues but I would stay away from them. First you'll need to upgrade the electric connection and they take some maintenance. The water must have a minimum flow before the heat is turned on. It needs to be sized to meet the cold water temperature and the demand if heated water. Many have good luck with them and others are problematic from reading many post on this forum. Gas units have more issues than the electric ones.

good luck.
 

oneskinnydave

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Thanks all for the super helpful input - .02c, etc :)

I think I'm just going to go with a 50 gal hybrid - look for the one that has the highest combined recovery rate (though I think they are all similar) - and then definitely do a tempering valve and leave room to figure out a recirculation system. Seems like the best way to have an efficient WH, and maximize the tank size! Recirc might be funky the way the hot water branches out - we have a wacky house that had a few additions and then we re-piped but I might have 2 of the valves at the extremes of the plumbing see if that works.

I'm just more annoyed that literally this week all the prices jumped and the rebate went away!

Thanks all for the all the insight, I really appreciate it!
 

jadnashua

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Utilities generally set up a budget for any rebates, and once they're gone, they're gone until the next year. I ran into that when I bought a new smart thermostat...it was near the end of the year, and they'd just exhausted their budget, so it ended up costing me $100 more than I had planned...best to do some of this right after the first of the year so that their new annual budget for rebates is fully funded, assuming you can wait...it's only a few weeks.
 

oneskinnydave

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Utilities generally set up a budget for any rebates, and once they're gone, they're gone until the next year. I ran into that when I bought a new smart thermostat...it was near the end of the year, and they'd just exhausted their budget, so it ended up costing me $100 more than I had planned...best to do some of this right after the first of the year so that their new annual budget for rebates is fully funded, assuming you can wait...it's only a few weeks.

Yeah - I was trying to get any info from my electric company about that - but they aren't allowed to discuss it. I might keep trying to call back and see if I can sweet talk someone into dishing it out!

The most annoying part of the process is AO Smith is giving me 30 days for the RMA to be valid - so I only have until the end of the month! I'm going to try and call to see if I can have it extended given the circumstances...it does seem like it's up to whomever I get on the phone how flexible they are!
 

Tuttles Revenge

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Last time I read the instructions for a Heat Pump water heater, they strongly discouraged the use of a hot water recirculation system.

Found it! When I first came across this discouraging info, it was more like the warranty was voided or halved if you installed a recirc. Now it appears that it just needs to alter the software to adapt to your recirc system

https://rmc-cdn.s3.amazonaws.com/si...-bulletins/Heat+Pump+w-recirculation+1331.pdf
 
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Fitter30

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Last time I read the instructions for a Heat Pump water heater, they strongly discouraged the use of a hot water recirculation system.

Found it! When I first came across this discouraging info, it was more like the warranty was voided or halved if you installed a recirc. Now it appears that it just needs to alter the software to adapt to your recirc system

https://rmc-cdn.s3.amazonaws.com/si...-bulletins/Heat+Pump+w-recirculation+1331.pdf
Since elements energize 15* below setpoint and heatpump starts at 25*. Problem would be minimized when using a timer or occupied sensor for recirc pump. Water should be hot before anyone would start to use it
 

Master Plumber Mark

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My plumber is pretty old school, recommends the cheapest tanks and let it run till it dies (hopefully under warranty) and get a new one. He did also recommend an 80 gal light commercial which is also on the table, but I do love the idea of saving electrical costs with a hybrid (we're all electric, no option for gas/propane here) so every little bit helps.


I am old school too.... keep it simple stupid..... KISS

Just install a Rheem 80 gallon lifetime electric water heater and live happily ever after
it will cost about 1600 plus install....

Stay away from all the fancy stuff and you will be happier.... throw a blanket on the new unit
if it makes you feel more ecologically at one with Joe Biden and the universe....

also those heat recovery coil pipes that go on the drain line to capture heat totally suck.....LOL
 
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