Size and type of water heater for showers

[Mike P]

Hi, i'm looking for a little advice. I currently have a Viessmann 100-W boiler and a 79 gallon electric water heater. Shower 1 has 6 body sprays, 1 shower head, 1 rain head, and 1 hand held. Shower 2 is just a tub/shower combo. Shower 3 has 4 body sprays, 1 rain head, and 1 hand held. Living by myself now the showers are not an issue, but I have lost my business due to COVID so I will be airBNB'ing the secount floor. The 79 gallon is def. not going to be enough. I wont have the funds for a proper solution yet so i'm trying to figure out the best approch. Showers 1 & 2 are upstairs. Shower 3 is downstairs for me. I was thinks of adding a second 100g electric water just for the biggest shower. The other 2 showers can share the 79 gallon. Or I can do the same and pipe them togerther. I have access to add a point of demand hot water the the upstairs shower 1 if that was a better idea. Or would installing a new Veismann 200 combi? the heating porthion of the boiler is 7 rooms of radiant heat aprox. 4K of tubbing. Handle everything, adding a indirect storage tank later if needed.

Thanks in advance,

Mike

 

[Twowaxhack]

Just get a couple tankless heaters. One for the rental and one for you.

 

[Mike P]

A tankless will make enough hot water for the large shower?

 

[Twowaxhack]

A tankless will make enough hot water for the large shower?

You never said how many GPM you need but typically yes.

Use two of you need it, but tanks are not the way to go.

 

[Mike P]

Looks like the biggest shower is about 21GPM. 6 sprays @ 2.5GPM ea, Shower head aprox 2.5GPM and rain aprox 4 GPM.

 

[havasu]

What size water lines do you have leading into that shower?

 

[Mike P]

3/4" feeding the DTX manafold then 1/2 balanced loops for the bodys and 1/2' for the head, rain head, and hand held. 1 1/2" each

 

[Twowaxhack]

Looks like the biggest shower is about 21GPM. 6 sprays @ 2.5GPM ea, Shower head aprox 2.5GPM and rain aprox 4 GPM.

Then a 100 gal. Tank would last about 4 minutes. So how long do you want people to be able to stay in the shower running 21 gpm ?

 

[havasu]

I believe your 21 GPM is unachievable with that set up.

 

[Mike P]

Im trying to figure out my options

 

[Twowaxhack]

I’d use 4 large tankless linked together and limit the body sprays to 1.5gpm.

 

[Mitchell-DIY-Guy]

I believe your 21 GPM is unachievable with that set up.

Agreed. Also a completely bizarre setup. Cap off a few of those, you don’t need them and neither do your tenants. Most people used to 1.6-2 gpm. 3-4, they’re ecstatic. You don’t need 21 and neither does anyone else. Beyond ridiculous. Save your $$$$.

 

[Geofd]

Can't you cap off/valve off all but on shower head in each bathroom so it's usable until your situation changes?????

 

[Mitchell-DIY-Guy]

A tank is a built in shower time limiter. As long as you supply something normal (like a 40 or 50) and NORMAL shower facilities that’s providing all you need.

Four tankless is as ridiculous as 21gpm.

 

[Twowaxhack]

A tank is a built in shower time limiter. As long as you supply something normal (like a 40 or 50) and NORMAL shower facilities that’s providing all you need.

Four tankless is as ridiculous as 21gpm.

Plenty of things are ridiculous but the question was asked.

 

[Mike P]

I currently get plenty of hot water, just 4 sprays and head going. lasts quite awhile at 103-105. But thats just myself, I'm going to go with thw Viessmann 200 and a 120 storage tank to start. Thats for the largest shower and new addition radiant heat and keep the 100W for the old radiant heat and the 79 gal electric HWH for the other two showers. Then upgrade in the future.

 

[TomFOhio]

Do you have a pressure pump added to the system to get to all those heads and body sprays

 

[Ludington]

I think I would drown with all that water.

 

[Mitchell-DIY-Guy]

Plenty of things are ridiculous but the question was asked.

I provided basically unlimited hot water to my customers at the car wash. Only an 80 gallon storage tank, but a 1.2M BTU/H boiler about the size of a Honda Fit. Reliability was the key, so only an atmospheric 80% efficient model. Great setup if you need a lot of hot water for large consumption. My four spray wands did about 1.2 gpm. The automatic was about 25 gpm but very brief stints with tempered water.

A nearby competitor had 5 x 200K tankless Takagi units with a sequential controller. Much less space. Much more efficient and a plumber’s field day.

Whatever works.