Tankless water heater & Recirculation Pump

[newlyold]

Yes, I have experience with tankless and recirculation. It saves gas, according to the EPA/GOV sites. It requires annual paid maintenance to keep it in shape, and monthly home maintenance by me to keep it running. When there are issues, they are expensive to repair--I spent $1300 a few years after it was installed, as the factory certified plumber tried to get it going again for me. Trip after trip, replaced part after part. Finally the main computer board was replaced and it began working properly again. So much for any savings in propane that year! I like their theory, and we do NOT run out of hot water, no matter how long a shower anyone takes, nor how many loads of laundry are running. But it has ended up be much more expensive to maintain and repair than I expected. I want something that just works, that doesn't need monthly cleaning by me, and that doesn't require an annual visit by the plumber to clean out the carbon / ash build-up that I can't access inside the fire chamber.

[FlaGator]

“Monthly cleaning” is a new one for me.

My 5 year old natural gas-fired Rinnai has worked flawlessly in a house of 3+ for five years. Zero maintenance. Not going back to a tank heater

[geezee1957]

We have and have previously had both. Switched one house to on demand. Seemed to save about $15/ month over a typical 40-50 gal gas heater. Sold that one a few years ago. Now have a different place. It had a gas 50 gal. We switched to a Rheem tankless last year. Much the same as far as savings. It is easy to tell because that is the only gas fired appliance we use in the summer. Normal bill for the two of us is 35 a month. I have a crawl space so I installed a recirc pump, and return line. Because I didn’t want to circulate hot water all day, I put the pump on a smart plug. I now say “Alexa start the hot water”. I have it set to run for 3 minutes. Working for us, and doesn’t waste water or gas.

[Safe Harbour]

We have had two Rheem tankless gas water heaters plumbed into a recirc loop for 11 years. It works great, but is very expensive to keep a heated loop warm. I put a timer on the system to turn the recirc loop off from 10.30pm to 6am. That saved quite a lot. The system had a small 10 gallon electric tank water heater to keep hot water for the loop. You don't want to the on demand kicking on every few mins to keep a loop warm, it's very bad for the heater and very inefficient as it has to heat up every time and then loose that heat in cooling down. Electricity for the 10 gallon tank water heater keeping the loop warm was a major electric drain, but better than the having the instant demand gas heaters cycling all the time.

But I finally hit on a better solution. The 10 gallon tank water heater finally rusted out so I had to replace it. I decided to go with a 40 gallon Rheem hybrid water heater. When it's working as a heat pump it uses only about 1/4 the electricity of a traditional (element) tank water heater. It's also highly programable and I have it set to go off at 10.30pm and on at 6am. We so seldomly use hot water during that period, I don't worry about relying on the tankless heaters then and knowing they will take awhile to fill the loop.

The Rheem only cost $1,100 and you get a $300 tax credit for energy efficiency. It is saving about $500 a year in energy costs. So payback is about 2 years and then it's all savings. Not a better energy efficiency investment to be had. It also saves gas because the loop runs longer without support of the instant water heaters. They only kick on when you use a fair bit of water from the tank.

Anyway, I'd put this system up against another arrangement for gas instant water heaters, unless they were all point of use. Also if you just have an normal element tank water heater, it will pay you to replace it now, regardless of age with a hybrid. They are so easy to put in they are basically plug and pay with a traditional tank water heater.

[zinger1457]

Quote:

Originally Posted by geezee1957 We have and have previously had both. Switched one house to on demand. Seemed to save about $15/ month over a typical 40-50 gal gas heater. Sold that one a few years ago. Now have a different place. It had a gas 50 gal. We switched to a Rheem tankless last year. Much the same as far as savings. It is easy to tell because that is the only gas fired appliance we use in the summer. Normal bill for the two of us is 35 a month. I have a crawl space so I installed a recirc pump, and return line. Because I didn’t want to circulate hot water all day, I put the pump on a smart plug. I now say “Alexa start the hot water”. I have it set to run for 3 minutes. Working for us, and doesn’t waste water or gas.

You must have some very high gas prices and/or a very inefficient water heater. I have a gas (propane) water heater (40 gal) and during a typical month when I'm not using the furnace (cooking and hot water only) I'm probably using about $10-15/mo of propane.

[mpeirce]

Quote:

Originally Posted by LA_Newsboy For those with a recirculation pump, what make is it, and would you recommend it?.

Some of the TWHs have an integrated pump. Just an option…

[tb001]

Quote:

Originally Posted by Safe Harbour We have had two Rheem tankless gas water heaters plumbed into a recirc loop for 11 years. It works great, but is very expensive to keep a heated loop warm. I put a timer on the system to turn the recirc loop off from 10.30pm to 6am. That saved quite a lot. The system had a small 10 gallon electric tank water heater to keep hot water for the loop. You don't want to the on demand kicking on every few mins to keep a loop warm, it's very bad for the heater and very inefficient as it has to heat up every time and then loose that heat in cooling down. Electricity for the 10 gallon tank water heater keeping the loop warm was a major electric drain, but better than the having the instant demand gas heaters cycling all the time. But I finally hit on a better solution. The 10 gallon tank water heater finally rusted out so I had to replace it. I decided to go with a 40 gallon Rheem hybrid water heater. When it's working as a heat pump it uses only about 1/4 the electricity of a traditional (element) tank water heater. It's also highly programable and I have it set to go off at 10.30pm and on at 6am. We so seldomly use hot water during that period, I don't worry about relying on the tankless heaters then and knowing they will take awhile to fill the loop. The Rheem only cost $1,100 and you get a $300 tax credit for energy efficiency. It is saving about $500 a year in energy costs. So payback is about 2 years and then it's all savings. Not a better energy efficiency investment to be had. It also saves gas because the loop runs longer without support of the instant water heaters. They only kick on when you use a fair bit of water from the tank. Anyway, I'd put this system up against another arrangement for gas instant water heaters, unless they were all point of use. Also if you just have an normal element tank water heater, it will pay you to replace it now, regardless of age with a hybrid. They are so easy to put in they are basically plug and pay with a traditional tank water heater.

Hmm, that’s interesting. We still have one functioning water heater and I asked them about using it as a reservoir for the recirculation but they said it wasn’t possible. Maybe because the recirculation pump is built in to the TWH?

I have to admit, I’m excited to get all of the space in the closet back. Two large water heaters take up a lot of room! It’s in an outside closet, so all of our gardening equipment, sprinkler repair, etc, will be finding a new home!

[Lakedog]

My current house has a tankless (no recirculation pump) mounted on the house exterior near the master bath so hot water takes only a few seconds in the master. For the two baths at the far end of the house, hot water takes just over 2 minutes (timed it after reading some of the replies to this discussion). The kitchen and another bath are closer to the center of the house, and it takes just over one minute for hot water. I can live with these short delays. I live alone and the spare baths are rarely used. The typical single tank water heater does not provide instant hot water to all parts of the house either so not what I see as much of a problem.

[ncbill]

Quote:

Originally Posted by newlyold Yes, I have experience with tankless and recirculation. It saves gas, according to the EPA/GOV sites. It requires annual paid maintenance to keep it in shape, and monthly home maintenance by me to keep it running. When there are issues, they are expensive to repair--I spent $1300 a few years after it was installed, as the factory certified plumber tried to get it going again for me. Trip after trip, replaced part after part. Finally the main computer board was replaced and it began working properly again. So much for any savings in propane that year! I like their theory, and we do NOT run out of hot water, no matter how long a shower anyone takes, nor how many loads of laundry are running. But it has ended up be much more expensive to maintain and repair than I expected. I want something that just works, that doesn't need monthly cleaning by me, and that doesn't require an annual visit by the plumber to clean out the carbon / ash build-up that I can't access inside the fire chamber.

Yep, is there really sufficient advantage to tankless over connecting a couple of 40 gallon (max capacity) "short" NG tank heaters down in the crawl space like my mom did at her last house?

[wildsun]

What is involved in Descaling and how long does it take to do that once a year?

[mpeirce]

Quote:

Originally Posted by wildsun What is involved in Descaling and how long does it take to do that once a year?

You circulate a mild acidic solution through the unit for maybe 45 minutes. Then flush that out of the system.

There are various valves to fiddle within the units.

Easy, but takes some time. You need a pump and some solution.

Look on YouTube if you want to see how it’s done.