The math of tankless water heaters

[Adolf Allerbush]

Looks like I am going to enter the market for a new hot water tank...

I currently have a 40gal gas Rheem tank that is in need of replacement. Right now I have just lost hot water pressure. I have drained and filled hoping it was a sediment issue but it looks like the tank is just slowly dieing.

After reading the threads I was wondering if anyone has any other ideas floating around?

I'm looking into the on-demand systems, which I know is a more expensive option, and the tank option will be a self installed deal since all the piping and venting is in place.

There seem to be a lot of options cropping up brand wise and I'm wondering if there are some that are better than others.

Just looking for thoughts and opinions.

I've been thinking about replacing the electric tanked hotwater heater in my house with a passive solar hotwater heater. A friend of mine has a passive solar system on the roof of his house and he says it works fine even though it's cloudy 9 months a year here.

[OSECS]

Looks like I am going to enter the market for a new hot water tank...

I currently have a 40gal gas Rheem tank that is in need of replacement. Right now I have just lost hot water pressure. I have drained and filled hoping it was a sediment issue but it looks like the tank is just slowly dieing.

After reading the threads I was wondering if anyone has any other ideas floating around?

I'm looking into the on-demand systems, which I know is a more expensive option, and the tank option will be a self installed deal since all the piping and venting is in place.

There seem to be a lot of options cropping up brand wise and I'm wondering if there are some that are better than others.

Just looking for thoughts and opinions.

Renai gas system. Should pay for itself fairly quickly + Isn't there a rebate out there ??

[mock vomit]

Looks like I am going to enter the market for a new hot water tank...

I currently have a 40 gal gas Rheem tank that is in need of replacement. Right now I have just lost hot water pressure. I have drained and filled hoping it was a sediment issue but it looks like the tank is just slowly dieing...

Lost hot water PRESSURE? My experience is that a failure of water heater almost always = hole rusted thru tank and water spewing out of bottom edge of it -OR- sometimes no hot water (from one cause or another)... Now I'm no plumber, and I've heard of sediment speeding up the rust thru of tank, but never heard of one failing with sediment impeding flow??? Just wondering...

Is it possible the restriction is from somewhere/something else? You have city water or well water? Need to use a water softener for hard water (for either city or well)? If on a well, do you have any rust/rust slime issues in your area? Have you tried opening the tap at bottom of heater to check if pressure there and/or lots of hot water (and drain some sediment)? Have you had only a slight drop in pressure, or a hudge one? Copper pipes or galvanized (especially the horizontals)?

[moose pit]

Lost hot water PRESSURE? My experience is that a failure of water heater almost always = hole rusted thru tank and water spewing out of bottom edge of it -OR- sometimes no hot water (from one cause or another)... Now I'm no plumber, and I've heard of sediment speeding up the rust thru of tank, but never heard of one failing with sediment impeding flow??? Just wondering...

Is it possible the restriction is from somewhere/something else? You have city water or well water? Need to use a water softener for hard water (for either city or well)? If on a well, do you have any rust/rust slime issues in your area? Have you tried opening the tap at bottom of heater to check if pressure there and/or lots of hot water (and drain some sediment)? Have you had only a slight drop in pressure, or a hudge one? Copper pipes or galvanized (especially the horizontals)?

This is a recent issue, 'bout two weeks, before that the cold water and hot water pressures were comparable. Now there is dramatically less hot water pressure than cold.

The good(ish) news would be that there is only about 2m of copper pipe between the tank and the first branch to a tap, so if the tank is fine and it is a restriction issue it will be in the closest section of piping to the tank.

As for sediment, I drained the tank and water flowed clear. It didn't flow when the cold inlet was shut until I opened some other taps so I was assuming that there is pressure - no leaks - in the system. After it was empty I gave it a couple blasts of water from the cold inlet to try and stir up any sediment and still nothing.

I was thinking it may be the pressure release valve? If it is fucked could it result in a loss of pressure? Since the tank isn't leaking I'm at a bit of a loss for a reason pressure would die.

[TeleHoar]

PSI safety won't affect your pressure, it is just a safety device that opens up at a certain pressure. (keeps your WH from becoming a bomb)

Aerators could be checked, or some sediment got stirred up and is stuck somewhere reducing flow.
Check that the supply stop valve is open all the way (left/CCW) under the sink.

Double check your other valves you may have closed off while filling/draining the tank to make sure they are full on open.

You could havew some air in the line, bleed off water at the highest points in the house.

?
Good luck.

[moose pit]

PSI safety won't affect your pressure, it is just a safety device that opens up at a certain pressure. (keeps your WH from becoming a bomb)

Aerators could be checked, or some sediment got stirred up and is stuck somewhere reducing flow.
Check that the supply stop valve is open all the way (left/CCW) under the sink.

Double check your other valves you may have closed off while filling/draining the tank to make sure they are full on open.

All the valves are good, the loss of pressure is in every hot tap in the house so I doubt the faucet aerators are an issue.

I might drain and fill again, sucks but doesn't suck as much as installing a new hot water device.

When I filled the tank last I left all the hot faucets open until they started to flow then closed them from the closest to farthest from the tank. I think if there was air in the pipes that would have taken care of it, or at least I hoped.

[The Dude]

I lost the water pressure for hot water last summer and it ended up being the mixing valve had too much build up in it, had to replace it and afterward, everything worked fine.

[moose pit]

What is this "mixing" valve?

Where can I find it?

[The Dude]

I've got a well system that pumps water to the pressure tank, then splits to the taps for cold water and to my 'indirect' hot water tank. The hot water coming out of the tank is way too hot, so it is mixed with the cold water from the pressure tank to make the water more tolerable.

The mixing valve in my system is located on the output of the hot water to the tap, the pipe to the tank has a T in it, one goes to the tank and the other goes to the mixing valve. The mixing valve has a large handle to turn with numbers (as a reference for adjustments) on it to adjust the amount of cold water being mixed with hot water.

We unfortunately found out the valve was completely blocked by calcium buildup, so we had to have a plumber come in and cut out the valve and then install a new valve along w/ soddering in some replacement pipe.

hope that makes sense.

[runethechamp]

You need to not have the regulators choked down to 4 inches of water in the pressure gauge from 7... but I'm just parroting what our contractor friends tell me. The standard pressure in a house is not sufficient to run all gas appliances simultaneously if you have a tankless system, because those systems need a lot of available pressure to run efficiently.

You just need bigger pipes, that's all.

[P_McPoser]

You just need bigger pipes, that's all.

I dunno, I am going to add another 48MMBTU soon and the line coming into our property also services residential customers. Sounds like sales pitches to me as well.

[moose pit]

I have a tankless .....no surging at all......and cooled off the laundry room by a good 20 degrees in the summer by not having a big tank of hot water PLUS way more room. Bought it at home depot. Brand is Paloma......installed it myself. LOVE IT

Gas or electric. Pretty simple or a cluster fuck that requires several cool down periods and a case of beer?

I'm looking at gas so I'd like to install one in someones house as a test run, ya know just in case

[OSECS]

Don't install an electric tankless water heater. The gas option is the way to go, especially if you already have gas.

[Bandy1080]

I like in the city and I am thinking about switching to a electric tankless water heater. Gas is not an option. Is this something I should even consider doing?

[OSECS]

I like in the city and I am thinking about switching to a electric tankless water heater. Gas is not an option. Is this something I should even consider doing?

From what I've heard from contractors, don't install an electric tankless. Very expensive install charge and not the efficiency of the gas, so savings don't add up for quite a while.

[moose pit]

Well I did a bunch of looking around and it looks like one tank is essentially as good as the next (some are the same just with different branding). So it looks like around 750 for the tank and the install. Since the Gov is big into rebates I also checked out a new furnace. 2500 tax rebate on the high end Lennox G71MPP (basically half off) now I just need to wait until september to get them done.

[OSECS]

Well I did a bunch of looking around and it looks like one tank is essentially as good as the next (some are the same just with different branding). So it looks like around 750 for the tank and the install. Since the Gov is big into rebates I also checked out a new furnace. 2500 tax rebate on the high end Lennox G71MPP (basically half off) now I just need to wait until september to get them done.

Is that half off unit price only or half off unit price and install combined ??

[BSS]

Well I did a bunch of looking around and it looks like one tank is essentially as good as the next (some are the same just with different branding). So it looks like around 750 for the tank and the install. Since the Gov is big into rebates I also checked out a new furnace. 2500 tax rebate on the high end Lennox G71MPP (basically half off) now I just need to wait until september to get them done.

HUH? I'm pretty sure the max credit you can get is 30% of the cost of the unit NTE $1500. Where are you getting this number from?

[moose pit]

Got the number from the retailer it is for the unit and install. As far as the rebate goes the deal seems to be you get a "energy efficiency" home inspection ($150) that makes you eligible for the rebates depending on the age of the current unit (the increase in efficiency) and is dependent on a subsequent assessment after the installation. The rebates are in the form of a tax credit so there may be a few hitches but it breaks down as $790 from the fed, $1130 from the province and between 540 and 680 in a renovation tax credit as well as a possible %10 home owners insurance break.

[BSS]

Oh, Canada... : slaps forehead :

That's a smokin' deal!

[OSECS]

See Canada can do that cause they haven't screwed up their financial system like we have here.

[OSECS]

See Canada can do that cause they haven't screwed up their financial system like we have here.

[moose pit]

See Canada can do that cause they haven't screwed up their financial system like we have here.

He he he he... ahhhh, don't worry our politicians are working to catch up. Vancouver 2010 anyone...

[Blatant]

danno, try searching this, there is a shit load of info on here. I actually posted regarding it as well. I didn't read the 3 pages, so if someone has alluded to this already... I'll stfu.

[mock vomit]

I STILL don't think it's a "failed" water heater based on what you've written??? Or maybe they just don't "fail" this way around my area? Without rereading thread to refresh my memory on specifics, if current unit is 12 or 15 or more years old, replacing it might be part preventive maintenance I suppose. But if you aren't 100% sure what the specific problem is, be prepared for possibility you replace it and pressure is still low!!! But if HWH is under 10 years old, and especially if you don't want to spend money on a water heater now, I'd either call in a plumber or try something else to check it more yourself? Please make sure to report back and let us know what the issue ended up being... That's my favorite part of these threads, well, after the helping out Mags part anyway.