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DIYtestdummy 02-05-2008 09:52 AM

Recommend Tankless Heater?
I really want to give tankless a shot. I, myself, waste at least 5 gallons of water waiting for the shower to even get warm. Windows out to the garden are planned for the remodel of both baths because of this, and water is expensive around here. The water heater is all the way at the other end of the house, and even after warmup, the pipes get cold and the process starts all over again if the second person has to shower, or even use the sink. Heck, the kitchen sink is only 14 feet from the tank and it takes a while to warm up.

I've seen some units sell for as little as $200. I don't know anyone who has a tankless, so I don't know if that's money well-spent. I'd prefer electric, since I want to put it on the bath side of the house, and running a gas line that far seems nutty. If it would be better to just replace the old tank with a tankless (gas) that would be okay too.

What are some good models and what is involved with install? DIY, no?

jogr 02-05-2008 12:17 PM

The electric tankless require a lot of amps so instead of a gas line you'll be running some big copper wires which are a little pricey now. You may not have a big enough electrical service to run an electric tankless. If you're incoming water is very cold in the winter you may not be happy with how warm the water gets. Maybe not a problem in Arizona. A gas tankless will generally do better if you have to heat the water up a lot during the winter. But a gas tankless can require a pretty large gas line.

Since your main problem is the water cooling off in the long pipe runs I would suggest first insulating your current hot water pipes.

If after insulating the pipes you still want further improvement then I would suggest looking into a small pump that will attach to the end of the long run and that monitors the hot water temp in the line. When it senses that the water is getting cool it pumps the water over into your cold line until the water becomes hot again. You could probably put a timer on this so it isn't on all the time.

Here is one example but there are other manufacturers:

DIYtestdummy 02-05-2008 02:27 PM

I can't insulate pipes that are in concrete. I think that's the main problem. I live by a man-made lake and it gets unusually cold. I'll insulate what I can when I open up the walls. I've looked at pumps, but I keep hearing that they are noisey and aren't really cost-effective. If I can time the operation noise won't be a problem. Will one unit work for 2 bathrooms?

jogr 02-05-2008 03:06 PM

Bummer on the HW pipe under concrete.

Don't know how noisy the pumps are. I bet you can find a fairly quiet one. You could put a motion sensor switch on the pump so that when you walk in the bathroom it will start pumping if needed.

I'm guessing some variation of the pump will be a whole lot cheaper than other alternatives.

One pump might work for two baths if they are close to each other. In that case you wouldn't want the motion detector. You would just want it to maintain the temp at all times (except possibly have a timer to shut off at night and during the day when people are gone). The other bath might have a short wait for hot water.

DIYtestdummy 02-06-2008 01:53 PM

Thanks! You wouldn't be related to the hockey player, would you?

jogr 02-06-2008 02:02 PM

No relation that I know of.

LawnGuyLandSparky 02-06-2008 03:07 PM

If you have copper pipe buried in or under a concrete slab, then here's a better fix for your predicament: (Keep in mind every time you use HW from the other side of the house, you're heating everything surrounding that pipe if it's not well insulated.)

I'd run 2 plastic PEX over the attic from the WH to the bathrooms and feed them from that. 3/4 for the supply. 1/2 for the return. Run the return line to a check valve and plumb it into the bottom WH drain with a T. (So you still have a drain.) Insulate both supply & return pipes.

If natural convection works, you're golden. If it doesn't, you can add a recirc pump that runs intermittantly.

What you'll spend doing all this is much less than an entire new WH, or an on demand tankless gas or electric.

DIYtestdummy 02-06-2008 11:35 PM

That'd be great...if I had an attic. This is a single-story, flat roof, built on a slab. I thought about snaking something through next to the HVAC ductwork, but then I'd be heating my cool air in the summer (oh-no!), it would be noisy, and I'm sure would violate all kinds of codes. There's always solar heating, but I don't wanna cut holes in my roof. It would be nice if I could run the lines under the porcelain tiles (throughout most of the house) and warm them up a bit. That would truly justify a pump and I could locate it somewhere else. <sigh> If I'm ever crazy enough to put myself through the torture of jackhammering the new tile...

Michael Thomas 02-07-2008 09:12 AM

I have various models of Takagi tankless WHs at my home, my office and at 3 of our rentals. They are now working well, but we encountered a number of issues when installing them. I have a web page up where I discuss some of the problems we have encountered, and how to avoid them. It also has some information of calculating the payback of tankless heaters:

jogr 02-07-2008 09:21 AM

I found a pump here for $235. You won't need to run any lines and can install it under the sink. A pump like this is your cheapest option. You may even be able to find a similar one for less.

moneymgmt 02-11-2008 08:26 AM

Maybe I'm missing this bit of info, but where are you going to install the tankless heater? The heater isn't the problem, like Jogr said, the length of the runs is. I have an electric tankless and swear by it, I'll talk to you all day about them if you want. I really don't think putting one in place of the tank is going to fix the problem you want fixed. You could go point-of-use, but as stated before, you're running #8 or #6 wire (depending on the unit) from your panel to the shower.... here it runs about $2.25/ft. The pump idea might be the better bet.

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