School me on hot water heaters...

[Matt_]

Closing on a house at the end of the month and the 18 year old hot water heater is getting swapped ASAP. Natural gas btw.

I have 4 kids, 3 of them being girls. My oldest (the boy) is currently 9, and the youngest girl is turning 4 this May….. so over the next ~10 year life this hot water heater is going to be very well used with 4 kids in prime teenage years. Add to that, im building an in-law suite for my parents who will be staying with us during the summer (in FL for winter). So I’m not worried about saving a buck or two since a slight benefit in efficiency will likely pay for itself many times over.

Anyone well versed in hot water heater options? There are now tankless options as well, and my heads starting to spin. Would it be worth doing a combination system? We’ll eventually have 4 full baths, with the upstairs 2 being the primary use, and the first floor & inlaw suite being more intermittent. Maybe do one setup for the current house setup, and add a smaller tankless unit when we build the inlaw suit which will be mostly dormant half of the year?

 

[RobW]

opposite- tankless for house, and smaller unit you can turn off or lower heat in winter.

may want to check your current water consumption and base it off that before taking a plunge.

pro tip- while youre at it, have plumber put a hot water bib next to outdoor hose for the winter car washes..

 

[rick81721]

Wow 3 girls plus your wife and mil? 1000 gallon tank!

 

[Matt_]

opposite- tankless for house, and smaller unit you can turn off or lower heat in winter.

may want to check your current water consumption and base it off that before taking a plunge.

We're currently in a 1 shower house and our 50 gallon has trouble keeping up at shower time. I usually go last and wait a bit or I'll run out of warm water..... and that's with yelling at the kids to hurry up LOL. It's also nat gas but nothing else special in terms of features

See I was thinking a fancy 60 or 70 gal for the main 3 bathrooms. They have heat pump hybrid models now too.... should I be going down that route?

And thought a small tankless unit for the inlaw suite would take load off the tank, but still be used in a pinch without having to wait for a tank to heat up. Also my parents wont use much water so wouldn't it be more efficient while they're here? Or am I thinking about this wrong...

 

[shrpshtr325]

the tankless will be more efficient because it doesnt keep a tank full of water hot, it heats it up as its needed (duh). I had a natural gas unit in my apt and never had any concern about running out of hot water, you could fill the bathtub without any change in water temp at the tap, i cant do that with the water heater in my house (unless i adjust the temp handle).

If i were you i would be looking at a tankless (i will be doing the same when ours is ready to be replaced), especially with 4 women (omg im so sorry) in the house using the water, its either that or do like @rick81721 said and keep 1000 gallons hot at all times if you want hot showers.

 

[Patrick]

I've been running tankless for 20 years. With low flow shower head, it can do two simultaneously. It is a smaller unit.

The alternative is to put in a second water heater and run them in series. Or a dedicated one for the suite, or master.

Running higher temps with smart valves can extend the available hot water too. Just don't scald anyone!!!

 

[trailhead]

I have tankless, but there are some issues to be aware of.
1) If your on a well, the fluxuation in pressure and low flow shower heads can cause the unit to shut off mid shower....very bad. Drill out the flow restrictor and use full hot for shower. If you need fancy temp mixers then skip tankless here.
2) you dont want the bathrooms on the tankless. People turn on hot water, splash and shut it off berfore the hot ever gets to the faucet, and meanwhile you just burned a bunch of gas. I have a 1 gallon electric water heater under the sink that serves both bathrooms.
3) Some High efficiency washers are programmed to dribble the hot water in, this causes many on/off cycles of the tankless and wastes gas. No correction available, I just tend to wash the dishes at the same as wash to make better use of the gas.
3) install requirements for the tankless are restrictive, if you have a large house this may not be an issue.

they make sense for intermittent, long term use of HW

 

[RobW]

We're currently in a 1 shower house and our 50 gallon has trouble keeping up at shower time. I usually go last and wait a bit or I'll run out of warm water..... and that's with yelling at the kids to hurry up LOL. It's also nat gas but nothing else special in terms of features

See I was thinking a fancy 60 or 70 gal for the main 3 bathrooms. They have heat pump hybrid models now too.... should I be going down that route?

And thought a small tankless unit for the inlaw suite would take load off the tank, but still be used in a pinch without having to wait for a tank to heat up. Also my parents wont use much water so wouldn't it be more efficient while they're here? Or am I thinking about this wrong...

your usage is probably up around 80g per day.

400,000+btu's if youre going further than 50ft to any bathroom/shower definitely consider a unit with a recirculating pump.

ive done some research so when it comes time, i know what i need to do for my own home. im going tankless (maybe sooner than hoped for)
this is the page ive looked at and still consider tankless unit. luckily for me, my brother in law is a master plumber and will do the install

https://www.thisoldhouse.com/ideas/read-you-buy-tankless-water-heater

 

[choop]

1 vs 5. I would skip the water heater and buy a nice tent.

 

[Dingo]

My parents have 2 water heaters. One is for kitchen and small bath, washing machine, dishwasher, other is for the bedroom/bathrooms.
Don't forget the dishwasher will be running too.

 

[w_b]

If I were paying for install, I'd get the largest tankless they make. Or maybe 2 mid-size ones, each feeding 2 showers, if that's possible. Tankless payback is long, but equipment should last longer, and ultimately have less total cost. That said, I never had one.

To ensure I am absolutely no help to you on this, with steady usage you can get 12-15 years on tanky heaters these days too. If I were DIY and there's a tanky there already I retrofit with what's there (or larger). Easy peazy.

 

[Matt_]

I'm handy enough to self install a replacement tank.... so that's definitely being factored in.

Didnt know about the other slight details of washing machine and dishwasher use. And yes the house is well. So much to consider

 

[RobW]

I'm handy enough to self install a replacement tank.... so that's definitely being factored in.

Didnt know about the other slight details of washing machine and dishwasher use. And yes the house is well. So much to consider

i believe dishwashers have their own heat exchangers to heat the water.... i will check out my PEX plumbing and let you know but i do believe the dishwasher heats its own water?

google says you can hook up hot or cold to it...

 

[michael.su]

Every time I change a water heater, I look at the tankless and it never really makes sense financially and with the amount of work I would need to do so I just end up swapping out for another tank heater, it’s too easy. (I have 3 separate apartments as well as my house)
Keep in mind, tankless was originally designed as “point of service” and I still think that it works best that way.
Having long runs of pipes...not so efficient...
Now when building a house, and you can design your plumbing with that in mind and use small heaters at point of service...bang, instant hot water and very efficient for water and gas/electric.

 

[michael.su]

i believe dishwashers have their own heat exchangers to heat the water.... i will check out my PEX plumbing and let you know but i do believe the dishwasher heats its own water?

google says you can hook up hot or cold to it...

I think this depends on the dish washer.

 

[Dingo]

I'm handy enough to self install a replacement tank.... so that's definitely being factored in.

Didnt know about the other slight details of washing machine and dishwasher use. And yes the house is well. So much to consider

Yeah, hot water sucks when it's cold. JK

 

[qclabrat]

I've been running tankless for 20 years. With low flow shower head, it can do two simultaneously. It is a smaller unit.

The alternative is to put in a second water heater and run them in series. Or a dedicated one for the suite, or master.

Running higher temps with smart valves can extend the available hot water too. Just don't scald anyone!!!

This is how our house was prior to a change, two in a series and recirculating. We went with a big single tank and took off the recirculating. If it hasn't already been done, if you may need to resleeve the vents if going up the chimney, and it's not cheap. We also have 4 bathrooms and 4 females in the house and we do sometimes run low on hot water. We saved a lot of money when we took out the recirculating, but it is nice not having to wait for hot water. If I were you, I'd try to get 2-3 tankless heaters on each side of the house as it sounds like it will be a long run. I'm also planning to add a BR in the basement, and planning to use a tankless instead of running another HW line.

 

[Patrick]

This is how our house was prior to a change, two in a series and recirculating. We went with a big single tank and took off the recirculating. If it hasn't already been done, if you may need to resleeve the vents if going up the chimney, and it's not cheap. We also have 4 bathrooms and 4 females in the house and we do sometimes run low on hot water. We saved a lot of money when we took out the recirculating, but it is nice not having to wait for hot water. If I were you, I'd try to get 2-3 tankless heaters on each side of the house as it sounds like it will be a long run. I'm also planning to add a BR in the basement, and planning to use a tankless instead of running another HW line.

Can always shut down one of the tanks if there are two.

Recirculators should be on a timer for mornings only. They can be done with a 5 gallon electric backed by tankless.

Might be cheaper to do point heaters under remote sinks.

 

[qclabrat]

Can always shut down one of the tanks if there are two.

Recirculators should be on a timer for mornings only. They can be done with a 5 gallon electric backed by tankless.

Might be cheaper to do point heaters under remote sinks.

We ended up putting the under sink units on the bathrooms on the other side of the house. Works well to supplement till the main supplies the right temp. Almost forgot about that, haha. I hate wasting water, waiting for it to heat up.

 

[JerseyPete]

No one suggesting indirect fired water heaters?
https://www.amtrol.com/product/boilermate-indirect-fired-water-heaters/

example: https://www.homedepot.com/p/Amtrol-BoilerMate-41-Gal-Indirect-Fired-Water-Heater-CH41Z/205193077

Honestly, I would echo what Michael.su said. It is cheaper and easier to swap out what is already in place, unless you are wanting to update the system.