Upgrade Hot Water Capacity for a Hot Tub
LESLIE: Ed in Michigan, welcome to The Money Pit. What can we do for you?
ED: Well, I installed a two-person Jacuzzi-type tub in one of the bathrooms in the house.
LESLIE: That sounds pretty nice.
ED: Aw, it’s fantastic. I currently have a 40-gallon gas water heater that just doesn’t supply the demand for hot water when I fill up this tub. Would it better for me to get an inline water heater? Or with some creative piping and valving, I should be able to put a second 40-gallon water heater in series with my current water heater.
TOM: When you say an inline water heater are you talking about a tankless water heater?
ED: That’s correct.
TOM: OK. Well, you definitely need more capacity. That’s the first thing. If you were to put a second water heater in, and a tankless water heater in particular, you would also have the ability to zone your hot water. Are you – do you ever find yourself, Ed, waiting, you know, quite a while for the water to get hot; say, in the master bath?
ED: Not really, no.
TOM: OK. So then you don’t really have a distribution issue so the only question here is what kind of a larger water heater do you want to put in. I would recommend against putting in two water heaters because two water heaters are not going to be nearly as efficient as one. What I would suggest you do is replace the 40-gallon with either a tankless, which will be certainly the most efficient way to go, or with a 50 or more gallon gas water heater with a quick recovery. Ed, whatever you do I would use the highest efficiency available.
ED: Well that’s my point, though. I don’t use this Jacuzzi-type tub very often; maybe once a week.
TOM: But if you put a second water heater in it’s going to stay hot all the time.
ED: Not if I turn it down.
TOM: No, no, no, no. No, it’s still going to waste a lot of energy. I would rather – if you’re concerned about energy efficiency I would suggest you get an on-demand tankless water heater. It’s only going to heat the amount of water you need when you need it. That would be the most efficient way to go.
ED: What kind of flow rate would you recommend?
TOM: Well, you’re going to get a flow rate that’s going to be based on the number of appliances in the house that you – number of fixtures in the house. That will be specified by the manufacturer. But you can buy one that’s appropriately sized for the number of bathrooms and the type of fixtures.
The key here, when you install the tankless by the way, is to make sure it’s piped correctly with the gas lines. Because even – those tankless water heaters use less gas but they use a larger volume of it just for a shorter period of time. So you have to make sure you have the right size gas lines in there and then it’ll work very well.
ED: Thank you very much.
TOM: You’re welcome. Thanks so much for calling us at 888-MONEY-PIT.