Gas or Electric Tankless?

[jeremybutcher]

Hi folks,

New here and first post so apologies in advance for any rookie post mistakes.

We’re remodeling our home in the Bay Area of N. California and would like to replace our existing water heater with tankless. We’re adding solar to the house so I’d really like to go with electric tankless if it can meet the heating demands of our family as the energy cost will be essentially free. We’re a family of 5 with 3 bathrooms. I think the odds of 3 simultaneous showers are very low, but I’d love to hear what folks have to say about if we can make it work.

Also sort of tough to make sure I’m finding the right data about the average water temp in our area to do the calculations. This look right: Average monthly water temperature in San Jose (California), United States of America - (celsius)

 

[SHEPLMBR]

You are not going to find an electric tankless to meet this demand. Not for a whole house situation.

 

[jeremybutcher]

thanks! is it silly to think about a "whole house" and an additional small one in a specific area? what do you think kills the deal here? water temp or family size? aka what's the biggest contributor to this not working? appreciate it!

 

[SHEPLMBR]

If you are wanting to go solar, I would recommend checking out specialized systems for solar.

 

[Twowaxhack]

What’s your objective ? Save money or save energy ?

Sometimes it costs money to save energy.

Initial install
Maintenance costs


Using electric tankless requires a lot of energy at once. So big wire and big breakers for little temp rise.

 

[jeremybutcher]

The goal is to save money (in the long run). We're adding solar with more capacity than our current consumption requires with battery backups as well. I'm trying to push as much of our consumption over to electric because it'll be cheaper than gas. I'm all for the up front cost of it because even if we break even it'll be better cash flow and the environmental impact is a huge plus in my mind as well.

 

[Twowaxhack]

Sure, get you an electric tankless. No problem.

 

[SHEPLMBR]

Again, I refer you to someone in your area that handles these types of things. Typically it is a tank heater with a storage tank.

 

[Twowaxhack]

Again, I refer you to someone in your area that handles these types of things. Typically it is a tank heater with a storage tank.

I think he’s asking if he can use an electric tankless to supplement his complete solar system. Maybe I’m mistaken.

It can be done but it’s not cheap to install or maintain. None of what the OP is doing is cheap initially and it may not ever pay back after maintenance is accounted for..

 

[jeremybutcher]

Correct! If we have solar energy production, can electric tankless work. I'm really looking to see if there's a system that can match the expected flow needs of my family given the ground temp throughout the year. Would love any local referrals that folks have too.

 

[SHEPLMBR]

Even with regular electric, heating a whole house will not work with a tankless.

 

[Twowaxhack]

If you spend enough money you can find a system that will match your needs and be all solar and electric. Not a problem.

You’ll need a good plumber or an engineer to design it specific to your requests.

 

[Twowaxhack]

Even with regular electric, heating a whole house will not work with a tankless.

I don’t think he’s heating a whole house.

I believe he is wanting to install a solar water heating system that supplies more hot water than his family uses. As a supplement to the solar he wants to use a whole house sized electric tankless.

He might need two......I don’t know. But it can be done with solar and using electric tankless water heaters.

It’s going to cost some coin......

 

[jeremybutcher]

sorry, let me try to clear things up. it's solar panels for energy production, from Tesla. no interest in solar water heating. and it is for the whole house. the question is what does whole house mean? if we can successfully run two showers and a faucet simultaneously then I think it's compelling, but I wanted to know if folks think that vendor charts are inflated, etc...i.e. when they say "two showers they really don't do that well so you should expect it looks more like this"

btw, really appreciate the back and forth here!

 

[Twowaxhack]

If you think you’re going to run an electric tankless water heater off solar panels and batteries I hope you have a few acres of solar panels set up and more batteries than I would even know how to calculate..

Some people have to get their grid home electric service upgraded to run one electric tankless. It’s ridiculous.

Im done with this one. Have a good day.

 

[jeremybutcher]

If you think you’re going to run an electric tankless water heater off solar panels and batteries I hope you have a few acres of solar panels set up and more batteries than I would even know how to calculate..

Some people have to get their grid home electric service upgraded to run one electric tankless. It’s ridiculous.

Im done with this one. Have a good day.

Thank you! Much appreciated. You too.

 

[SHEPLMBR]

sorry, let me try to clear things up. it's solar panels for energy production, from Tesla. no interest in solar water heating. and it is for the whole house. the question is what does whole house mean? if we can successfully run two showers and a faucet simultaneously then I think it's compelling, but I wanted to know if folks think that vendor charts are inflated, etc...i.e. when they say "two showers they really don't do that well so you should expect it looks more like this"

btw, really appreciate the back and forth here!

no, what they say is max, is max.

 

[JG plumbing]

A combi boiler will heat all of your water and supply heat for your house.


Now I don't really like combi boilers becuse it's a tankless and they require maintenence.

But I'd have to look to see what your heating demands are. Have you had a heat loss Calc done?

If your going to look for a local contractor make sure they do a manual j heat loss Calc. If that's not part of the service they are going to provide move on and find one that will.