Water heater replacement, conventional tank to tankless
 

Well it happened again. The 2nd hot water heater started leaking.
I am going to replace the narrow trailer style gas hot water heater with a tankless gas water heater.
It is110,000BTU per hour 85% efficient unit. I figure it can raise the temperature of 3gpm of water about 62°F. Even with cold winter water it should still be able to heat the water up to 100°F at 3gpm. It cost $600 and has 4 inch intake and exhaust.
There were more expensive ones, $900 buys a 7.5gpm but the intake exhaust are 5 inch.
I have a 4 inch exhaust for the existing water heater and a 4 inch exhaust for a in wall heater that has been removed.
And I ran a wireceptacle for a tankless heater a few years ago while under the house rewiring some stuff.
So the intake and exhaust holes and electrical are already there. Just add water heater.

I installed this one Takagi T-H3-DV with 0.95 energy factor
http://ecorenovator.org/forum/renova...er-heater.html
You can use 3” or 4” PVC venting.
http://www.takagi.com/products/tankl...ters/t-h3-dv-n

This works great supper efficient. They make smaller models also. Here two people can shower and run water in the bathroom at the same time.

I have had a few tankless heater. I have been using them since I was a kid. This one is the best by far that I have used.

That's a pretty good one.
Seems a little big for me.
Just wondering how much does that one typically cost?
I only need enough to run a shower and maybe the dish washer.

This one might be better for you
T-H3J-DV-N - Takagi T-H3J-DV-N - T-H3J-DV-N Indoor Tankless High Efficiency Condensing Water Heater (NG)

T-H3J-DV-N - 160,000 BTU Natural Gas Indoor Condensing Ultra-Low NOx

This is the same as mine but 160,000 BTU

https://www.acwholesalers.com/Takagi...H0zBoCj2nw_wcB

If you have to buy vent pipe that is expensive. Make sure you add that to the total cost. PVC is very cheap to vent with.

I've been using a Bosch tankless (battery operated ignition) for almost 20 years.

Mine is a lower efficiency style, but except for an early ignition coil failure, it's been efficient hot water all the way.

I agree with above comments about the size being way too big. I believe the original thinking was to design a tankless that could be 'dropped-in' and replace a full four person family's DHW demands.

But you are not four people, and you are not likely to wash clothes, while you shower, while the dishwasher is running, while someone washes their hands.

I have looked at some of the Chinese units on ebay, and I think that for a guy living alone, one of those units would do it better than the whole house units.

Another consideration is that they do NOT supply instant hot water, there is a heating up curve. Not impossible, but it is there.

It is to your benefit to locate your tankless water heater as close as possible to the most frequently used water outlet. This is not the same as the highest volume outlet.

Good luck,

-AC_Hacker

I have one of the Chinese units I bought off ebay. It has battery operated ignition. It is a vent free model.

I bought it for the greenhouse. Most of these will not provide hot water more than 15-20 min at a time then they need a rest and they shut down.

Others have built closed loop heaters and they put them on a timer to rest them then run them again.
If you have any question on it or need pictures I have not installed it yet.

Search ebay, use "tankless water heater", or "demand water heater", or "vent free water heater"

You'll have lots of choices.

-AC

Another thing I don't like about the tank less is it seems unless you buy a big one they restrict flow.
My tankless heater is rated for 4.3gpm, I'm not getting anywhere near that much flow as compared to the old gas heater. The utility water pressure where I am is usually about 100psi.

This is our tank GPM
Maximum flow rate of 10.0 GPM at 35°F temperature rise (5.4 GPM at 70°F rise)
You need to know how cold your water it coming to the tank. As you can see it can make a huge difference if your incoming water is very cold and will reduce the flow.

Takagi web site uses pictures to show the flow.

http://ecorenovator.org/forum/attach...1&d=1483979582

It heats the water up just fine. I figure a 62°F increase even at 3gpm.
It will just not flow any more than about 3gpm.

I assumed a 35°F inlet temperature and told the wife that on really cold days she may have to slow down the flow to allow it to warm up more.

They have a screen at the cold water inlet. Sometimes that gets clogged up some.
See if that needs cleaned I have had to clean mine a couple times it will reduce your flow.

They also have restrictor washer at the clod water inlet. If you know you have warmer water you can increase the size of this washer this will let more flow.

Yeah I figured there might be a water restrictor.
I always check all new equipment and fixtures for water restrictors and remove them.
I didn't see any on the water heater.
Since I did install clean outs on the inlet and outlets of the water heater I can turn off the water and open the clean outs and send my probe camera in there to see.
It has been a year or 2 since that hot water line has been used much, so maybe the inlet screen is clogging with rust.

On very windy days the hot water heater likes to fault out and not light the burner. Or it will light for about a second and go out then fault.
Yes I have a chimney cap.

I don’t recall what brand and model you have.

The one I have is a marley.
I think it's the Lowes brand.

I'm using this tank less to fill our hot tub.
By my my calculations it's putting out 73,000btu per hour of hot water. That's like a commercial hot water heater.
I thought it would shut off after 20 or 30 minutes, nope it just keeps going and going and going.

If you need a lot of hot water this is the way to go.

In the next house we are getting I don't think I will use a tank less water heater on account of they waste too much water.

double post

How do they waste water ? never thought about the coming into play.

I was wanting to install one in this house until factored in having to upgrade the power supply so swapped in a new tank and called it done.

For the next place thinking a solar water heater for summer and a pellet / wood stove water heater for the wet winter weather. They could share a heavily insulated storage tank

The tankless waste water by the nature of their opperation.
When the water starts flowing it has to flow for so many seconds before the burner lights, then when it lights it has to get up to temperature.
Unlike a tank water heater where the water is at temperature already, so the hot water starts flowing as soon as the first drop.

We have it so when you turn on the bathroom light it starts the recirculation pump. We use a different amount of time depending how far you are away from the tank. This really helps that so no water is wasted here. We waste less water than a most tank heaters.
The hot water pipes and the return lines are all insulated.

I was going to wire it in on the light switch or put the circulation pump on a count down light switch timer.

I would in your place have installed several tankless water heater