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-   -   My next project natural gas tankless hot water heater. (https://ecorenovator.org/forum/showthread.php?t=3167)

pinballlooking 09-16-13 12:46 PM

My next project natural gas tankless hot water heater.
 
I just got delivered a Takagi T-H3-DV with 0.95 energy factor. This is a condensing unit so it just vents with 3” PVC pipe. http://www.takagi.com/products/tankl...ters/t-h3-dv-n
I am moving my tank from the attic to the garage. I have copper pipe now but I think I will try my hand at installing Pex. I am going to add a return line for the recirculation pump. I have an aquastat and a trimmer for the recirculation pump. I am going to put contact switches on the bathroom doors and use my home automation to turn on the recirculation pump 10 min when the bathroom door closes.

Daox 09-16-13 12:54 PM

Very nice unit. What are you currently using for hot water?

pinballlooking 09-16-13 01:01 PM

I have a Bosh AquaStar 170V. My family has grown since we put in that tank. It does ok but we could use more GPM now. My old unit has a pilot and was about 80% efficient not too bad. It also does not keep the water at as a steady temp as the new electronic controlled tanks.

The attic install was a mistake. It has a couple 60 watt bulbs that have to keep it warm in the cold winter. They are temp controlled to turn on and off but if the burn out it will freeze the hot water. This is just a bad setup and I am going to change this.

Daox 09-20-13 11:53 AM

Where is the new water heater going?

pinballlooking 09-20-13 12:03 PM

I am going to put it in the garage. This will shorten the hot water copper by at least 30 feet.
It came with a free isolation valves and pressure relief kit.
But that did not ship until today.

Daox 09-20-13 01:27 PM

Interesting you should mention the freezing problem. I have a Bosch Aquastar 125B (on demand gas with a pilot light) which I am not currently using. I got it for a real deal because the previous owner had it in their cabin and their main form of heat was a fireplace. Well that fireplace sucked in so much cold air through the water heater's exhaust pipe that it froze up and cracked the heat exchanger. They had it repaired, but decided to go with an electric hot water heater after that.

pinballlooking 09-20-13 01:50 PM

If you ever need parts you can still get some here.
Bosch Aquastar 125B Repair Parts / 125FX Repair Parts Tankless Water Heaters. Repair Parts for 125B & 125FX
I just installed a new water valve rebuild kit on my old one last week.
It is doing better now this bought me some time so I don’t have to rush putting in my new water heater

Daox 09-20-13 02:10 PM

Thanks. I believe its in running condition, I'm just decided to go with a smart electric on demand hot water heater instead due to my solar hot water setup I have in the works. I still might use it as a backup heat/boiler though. The efficiency isn't amazing, but it was like $125...

pinballlooking 12-30-13 09:57 AM

1 Attachment(s)
0.95 energy factor with no more pilot light burring gas. No more water in my attic and worrying about it freezing up there.

I installed my tankless water heater this weekend. This is the first time I have used MAPP gas for soldering copper. This stuff is so good I will never go back to propane. This is the first time I used PEX. WOW this stuff is such an improvement I just love this stuff.

I put in two Tee’s with PEX valves on the hot water at both ends of my house for a return line. I put in a Tee and a PEX valve at my hot water tank. I just need to run PEX and pipe insulation for the return line and put in a recirculation pump.

I was going to leave my old tank in place because it does not require power to run and only use it when the power goes out but it would not pass code I do not have enough gas supply to run both and no way to guard against this from happening. So I took disconnected the old one.

The new tank requires power to operate so we will not have hot water when the power goes out. I am going to charge a car battery with a solar panel. I bought a real sine wave inverter just a little bigger than it will require to run the new tankless unit. I need to experiment with how long the battery will last with my new inverter.


The new recirculation will have a aquastat and will be hooked up to my home automation.
The bathrooms we have new commutation light switches. When you turn on the bathroom light it will kick off the recirculation pump for a certain amount of time.

http://ecorenovator.org/forum/attach...aterheater-jpg

Daox 12-30-13 10:07 AM

Looks like a nice clean install, very nice.

Do the instructions/manual say how much power it draws?

I know some of the tankless gas units used a bunch of D cell batteries... I doubt it draws much power.

pinballlooking 12-30-13 10:16 AM

It power vents so the blower motor has the biggest power use.

Yes it uses 89 watts in operation and 4.2 watts in standby. 175 watts in freeze protection mode but it is in a insulated garage so it should not have to use the freeze protection mode.

Daox 12-30-13 10:17 AM

Wow, that is a lot more than I would have expected.

pinballlooking 12-30-13 10:22 AM

I would have liked it to use less power in standby. It can vent up to 100 feet so a blower motor is a must.
The Navien NR-240A-NG I was looking at uses 200 watts.

stevehull 12-30-13 11:24 AM

Quote:

Originally Posted by pinballlooking (Post 31663)
I have a Bosh AquaStar 170V. My family has grown since we put in that tank. It does ok but we could use more GPM now. My old unit has a pilot and was about 80% efficient not too bad. It also does not keep the water at as a steady temp as the new electronic controlled tanks.


Pinball,

Interesting. I also have an Aquastar 170VP (P for propane), purchased in 1987.. In that time, I have had to do a few fixes (thermocouples, rebuild kit for modulator value), but am thinking of another unit. My main gripe is that the water modulator valve does not keep water temp as well regulated (just the same as you) as I would like. It owes me nothing and has long since paid for itself (perhaps several times over).

How did you choose the replacement and how much $?

Oh, I forgot, with large winds, the pilot light of the 170VP would blow out, but this was easily relit. It would be nice to have electronic reignition . . .


Steve

pinballlooking 12-30-13 11:57 AM

Steve

I had all the same issues you have had 170V except for the thermocouples.
I finally increased the holes in the screen for the pilot light. So the pilot would no longer go out.

The 170V is 80% efficient so like me you won’t see a big savings switching to this tank. With no pilot you will see some.

I really liked the Navien NR-240A-NG my neighbor installs them. If you buy them over the internet they will not warranty them. They will not talk to a home owner for any repair so that ended me buying that one.

My neighbor the Plummer said stick to Navien, Rinnai, Takagi.
I almost bought a Rinnai but you have to use their special vent pipe and that stuff is so expensive.

The Takagi has a 15 year warranty on the heat exchanger even with a circulation pump control as long as you use a aquastat and/or timer
http://www.takagi.com/download/2013-Warranty-info.pdf
You vent it with 3” PVC this is cheap and I can easily do this myself. I love the Energy Factor of 0.95.

You can get a smaller unit but the bigger unit does not use more gas than the smaller one unless you are using lots of water at the same time. So it really does not make since to go with the smaller unit. The cost difference is not that much either. My Plummer friend told me don’t even consider on less than 199000 BTU’s

The electronic controlled water temp is so much better than on the 170v I did a long shower today and I did not need to adjust the temp at all.

The Takagi has free isolation valve and pressure safety valve kit deal. (this really saves money)

I bought it from build.com and found a coupon code. I paid $1,096.16 shipped with isolation valve kit.
Takagi TH3DV - Build.com
Mark

stevehull 12-30-13 01:01 PM

Ok, need some help here on what to do re water heater (fits right in with this discussion).

Old home, now for sale, has the 25+ year old tankless Aquastar 170. Next year, we are tearing down old farmhouse where we live now and rebuilding on foundation. Lots of reasons, but cast iron pipe plumbing is clogging up, old electricity/wires in house are bad, roof needs repairs, etc, etc, etc. We knew it was temporary housing when we moved here.

Anyway. I do heat/cool former and present farm house with open loop GT heat pump. In the summer (May - September), I have a loop from desuperheater that essentially fills a 55 gal electric water heater to capacity (120 F) each day (old farmhouse). I turned off one element as I super insulated this "preheat" tank. At least that is what I called it before I found out GT heat pump/desuperheater would fully heat it up in the summer.

I will move these (heat pump/water heater tank) out of old farmhouse and will reinstall in home when rebuilt. In meantime, while rebuilding, we will live in mobile home on property (also heated/cooled with GT heat pump and use an electric water heater storage tank for stored summer desuperheater water).

For the other six months, I have used electric resistance heat for this water, but I kick myself as this is one of the poorest uses of 1 phase 240 VAC. Clearly, in the mid winter, like now, I get almost no hot water from the desuperheater and use resistance heating for hot water.

I do have (and will have) propane so I could easily plumb in a tankless water unit in the rebuilt farm house, after the pre heat tank, to fire up if there is not enough hot water (turn off tank resistance elements).

My thinking is that my ROI is probably best just using the existing tank. However, we have LOVED the efficiency and use of the Aquastar as it supplied gobs of endless hot water. When we had three young children, this tankless water heater was a wonder to behold.

But it is hard to complain about essentially free hot water from the desuperheater for 1/2 of the year . . .

Thoughts?

Steve

pinballlooking 12-30-13 01:20 PM

In your situation a 40 gal gas energy efficient hot water heater with an active pilot would be good.
When you provide it hot water just the pilot would be almost enough to keep it warm. Then in the winter the tank could provide hot water at a reasonable price. The price to get one will be less than a good tankless heater.

stevehull 12-30-13 02:03 PM

Pinball,

Had not thought of that solution! You are correct that a high efficiency propane fired tank unit is far cheaper than a tankless. I can plumb the GT heat pump desuperheater heated tank in before the propane fired tank and turn off the electric resistance elements.

We have propane as we both dislike electric resistance element stoves and also use propane for the dryer (in winter). In summer, the clothes line works . . .

In thinking about this, I can actually use BOTH tanks to store water (clearly water not as hot) and have a larger reservoir of preheated water. First, fill the propane fired unit with desuperheater water and when that is full, fill the storage tank behind it.

Easy to do; just plumb the supply line with hot water from GT heat pump desuperheater and have the return line come from storage tank cold side.

Great suggestion.

Steve

pinballlooking 01-04-14 03:37 PM

I have added a small expansion tank , a check valve and a recirculation pump.
I did a loop back return with Insulated pex on my hot water line.

I added insteon home automation switches in the bathrooms and at the kitchen sink.
When you turn on the bathroom light I kick off the recirculation pump for a set amount of time. It depends how far the bath is from the tank as how long I run the pump. It either times out say for 2 min or when you shut off the switch it will also turn off the recirculation pump. I will also set it to run before the boys go to school because that is a set time each day.

I really like this setup I am not wasting natural gas by running recirculation pump all the time but I don’t have to waste water and wait a long time for hot water.


The only thing I have left to do is add in the aquastat and experiment with my inverter for when power goes out.

pinballlooking 01-10-14 03:30 PM

1 Attachment(s)
Here is a picture of the small expansion tank, a check valve and a recirculation pump.
It looks like an erector set now.

I also put in condensation drain the top part of the condensation drain I put in clear tube so I will always know if it is draining.

In another blog I saw where someone else put in a flow switch so whenever someone turned on the hot water they would kick off the recirculation pump. So if they went into the bathroom the would turn on the hot water for a couple seconds then when they came back the water would be hot. They also used a aquastat to save energy. (I like my setup better but his setup if cheaper to install)

I changed the bath to run the pump 30 seconds because it is close to the tank. This new tank is really working well it keeps the water a very constant temp unlike my old tankless water heater.

We keep our water pressure pretty high so that is why I added the small expansion tank.

ecomodded 01-10-14 11:26 PM

I had a look at the Specifications and was pleased to see it will run on Propane 13,000btu's or natural gas 15,000btu's.
I am in the running for a tankless water heater right now, I need to do more research..
How much does this model cost ?

pinballlooking 01-11-14 04:33 PM

Quote:

Originally Posted by ecomodded (Post 34707)
I had a look at the Specifications and was pleased to see it will run on Propane 13,000btu's or natural gas 15,000btu's.
I am in the running for a tankless water heater right now, I need to do more research..
How much does this model cost ?

The Takagi has a 15 year warranty on the heat exchanger even with a circulation pump control as long as you use a aquastat and/or timer
http://www.takagi.com/download/2013-Warranty-info.pdf
You vent it with 3” PVC this is cheap. I love the Energy Factor of 0.95.

The Takagi has free isolation valve and pressure safety valve kit deal. (This saves some money)

I bought it from build.com and found a coupon code. I paid $1,096.16 shipped with isolation valve kit.
http://www.build.com/takagi-th3dv-lp...21706_u3967755
But you can buy it a lot of places.
Mark

ecomodded 01-11-14 06:32 PM

thanks for the information , it is a expensive unit although a very powerful one 15,000 Btu's should do the trick. My propane Fireplace puts out the same Btu's as your heater.
I still need to get that pressure tested before I put it into service.

!5 yrs is a good guarantee some security with a warranty that long I expect cheaper units to have a 5 yr guarantee.

regards

Mikesolar 01-12-14 07:49 PM

ECO, it is 150,000btu, not 15,000. Most tankless water heaters are a minimum of 150Mbtu. I put in Navien regularly but have put in Takagi and Rinnai (same as Bradford White).

The cold snap last week has killed more than a few tankless heaters and I have been busy putting in new ones. I will never put the venting as close to the unit as was typically done and will ALWAYS put in fresh air thermal blocking so that the cold air cannot come in unless the unit is firing. On one I am putting in tomorrow (to replace a Takagi) the venting will be 12 feet long and the unit will not be on the outside wall.

On top of this, unless they insist, I will put in a Vertex or another high efficiency tank instead of a tankless. Most people will use the tankless the same what they used to use a tank, on and off, small amounts of water and the unit needs to go through a prepurge and sense the need for flow, light up, etc, then shut down again, sometimes without getting 1L of water to the tap. It is a waste. If I can use a Vertex or Polaris, assuming the heat load is right, I can eliminate a furnace or boiler.

pinballlooking 01-12-14 09:26 PM

Yes min is 19,500 max is 199000.
I have mine mounted in my garage on the inside wall. The air intake is in my attic. That keeps the wind from coming in the intake. The exhaust is about 25’ away.

My old tankless was a little smaller but Energy Factor of 0.80 my gas bill was $12.36 - $18.44 (this was summer bills when we did not use gas heat) this is with a $7.50 meter charge included. Not bad at all I was pleased with this. This is for a family of 4.

The new tankless does not have a pilot and has Energy Factor of 0.95 but we are doing intelligent water circulation pump. I will report back in the summer what the new gas bill is.

My neighbor has a Navien npe-240a that has Buffer Tank & Recirculation Pump included. Nice unit he likes it. My other neighbor that is a plumber puts lots of these in but if you buy them on the internet they will not honor their warranty.(no deal for me)


I looked up the Vertex hot water heater it looks very sweet. Wow it is expensive. I could have easily going for this tank if the cost was similar to my tankless heater it would be a great choice.

Mikesolar 01-13-14 05:11 AM

Quote:

Originally Posted by pinballlooking (Post 34746)
Yes min is 13,000 max is 199000.
I have mine mounted in my garage on the inside wall. The air intake is in my attic. That keeps the wind from coming in the intake. The exhaust is about 25’ away.

My old tankless was a little smaller but Energy Factor of 0.80 my gas bill was $12.36 - $18.44 (this was summer bills when we did not use gas heat) this is with a $7.50 meter charge included. Not bad at all I was pleased with this. This is for a family of 4.

The new tankless does not have a pilot and has Energy Factor of 0.95 but we are doing intelligent water circulation pump. I will report back in the summer what the new gas bill is.

My neighbor has a Navien npe-240a that has Buffer Tank & Recirculation Pump included. Nice unit he likes it. My other neighbor that is a plumber puts lots of these in but if you buy them on the internet they will not honor their warranty.(no deal for me)


I looked up the Vertex hot water heater it looks very sweet. Wow it is expensive. I could have easily going for this tank if the cost was similar to my tankless heater it would be a great choice.

Maybe I misread the post. I thought he was talking about the rated input of the unit. The min of 15mbtu is correct.

The Navien I am putting in is a 180 and will be with the buffer tank (you can get it with or without). The buffer tank is supposed to eliminate the sandwiching which it does but the evidence shows that the actual efficiency of the unit goes down somewhat from the non buffer tank model but everything is a tradeoff, I guess.

I don't know of any tankless that has a pilot these days and the old Bosch one was used for off grid solar because it did not need any power to light it up. I have put them in as well in the past.

The reason I mention the Vertex is because many tankless heaters don't last 10 years and we would expect any heater to do that. Much of the time it is because the circuits are going on/off a lot more than a tank control would. It also means that there is a lot of wasted gas for those who don't change their habits to meet the heaters abilities. Time will tell.

pinballlooking 01-16-14 04:00 PM

1 Attachment(s)
Quote:

Originally Posted by Mikesolar (Post 34747)
I don't know of any tankless that has a pilot these days and the old Bosch one was used for off grid solar because it did not need any power to light it up. I have put them in as well in the past.

Yes I was replacing a Bosh AquaStar 170V.



I charged up my new boat battery connected up my real sine wave inverter 150 watt 300 watt peak. It ran the new tankless heater fine while I was running hot water.

The battery is 50 AH we would use it then turn off the inverter off until we needed hot water again. It is good to know we will have hot water if the power goes out.

http://ecorenovator.org/forum/attach...1&d=1389909852

Mikesolar 01-16-14 05:37 PM

Quote:

Originally Posted by pinballlooking (Post 34824)
Yes I was replacing a Bosh AquaStar 170V.



I charged up my new boat battery connected up my real sine wave inverter 150 watt 300 watt peak. It ran the new tankless heater fine while I was running hot water.

The battery is 50 AH we would use it then turn off the inverter off until we needed hot water again. It is good to know we will have hot water if the power goes out.

http://ecorenovator.org/forum/attach...1&d=1389909852

I would be really careful that the inverter is pure sine wave, not modified because there is a lot of electronics (furnaces with ECM motor controls, for example) that will be destroyed by modified sine wave inverters. The ice storm we just went through forced a lot of people to get cheap generators to run the furnace or boiler, just to have the electronic board blow.

pinballlooking 01-16-14 05:46 PM

Quote:

Originally Posted by Mikesolar (Post 34830)
I would be really careful that the inverter is pure sine wave, not modified because there is a lot of electronics (furnaces with ECM motor controls, for example) that will be destroyed by modified sine wave inverters. The ice storm we just went through forced a lot of people to get cheap generators to run the furnace or boiler, just to have the electronic board blow.

Thanks for jumping in and sharing some of your experience. It is nice to see someone that is in the field that does not mind sharing info.

Good point. I paid the extra for a pure sine wave inverter and it is just big enough for the heater.

I have a generator but it is not a pure sine wave inverter so this is what I will use the inverter to run the hot water tank and not the generator.

wuck 01-25-14 10:16 AM

Quote:

Originally Posted by pinballlooking (Post 34528)
I have added a small expansion tank , a check valve and a recirculation pump. I did a loop back return with Insulated pex on my hot water line.

Nice job on the install Mark, the "smart" pump control is an excellent addition.

Where does the recirc loop return to? I'm guessing it runs back into the cold feed, triggering the heater when the pump is activated? I'm also curious about the aquastat install and how it is integrated into system.

I have a recirc pump on my NG fired conventional tank controlled by a simple timer. It's about 75 feet of 3/4" copper to the guest bath at the other end of the house, the pump is really a necessity. I added a 1/2" copper return line feeding back into the tank drain, with the total loop being around 150 ft. All lines are insulated through the crawl space.

I've thought about going tankless, moving the heater into an existing outdoor closet. The new location is adjacent to the kitchen and main bath, while the guest bath pipe would be cut to 30 feet or so.

Pat

pinballlooking 01-25-14 12:53 PM

Thanks we really like it. I really think it is the best of both worlds between saving water and natural gas.

Yes the recirc loop returns to the cold water side of the heater. I have a back flow preventer there so it only takes the path when the pump it running.
The aquastat installs over a copper pipe and mointors the water temp once it warms up past the set point it will take away the power to the pump. So this would work for your setup also it would turn off the pump once the water reached the aquastat temp once the water cools back off it will put power back to the pump.

This all works independent or over rides what my automation tells the pump when the water is hot.

No sense running the pump if the water is hot.

This is a good read it is more on rentals but it applies to us also.
Home Energy Magazine :: Money Down the Drain: Controlling Hot Water Recirculation Costs

pinballlooking 02-06-14 04:23 PM

1 Attachment(s)
We like the new tankless hot water heater. We keep the water @120 deg. This works good for the kids. But when I shower I like it hotter. We have a steam setting on the shower head. This really warms up the shower. It is a pain to go into the garage and change the temp. Then we have to remember to change it back.

My tank has a Takagi Temperature Remote Controller I just ordered. This will go in the master bath room we can turn up the hot water for the shower the back down.

This will also display additional error codes if it ever has issues (I hope I do not need that feature)

It would be nice if it was wireless but it is wired so I will have to fish one more wire.

They had free shipping and $25 off if you use V.me Visa.

http://ecorenovator.org/forum/attach...7603005-13-jpg

Mikesolar 02-06-14 04:44 PM

Do you find any issues at all with it? The most common ones are the time it takes to get to the taps and some of them will be hot, then cool, then stay hot. It is called sandwiching.

pinballlooking 02-06-14 04:55 PM

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 that is not much of an issue. The hot water pipes and the return lines are all insulated.

So if you just use a little water and turn it back off the pump keeps it running. This makes it less likely to have the sandwich effect.

We a happy with it so far.

Mikesolar 02-06-14 04:58 PM

That is a good idea....the light switch. I may try that when i do another tankless that is a distance away from the master bath.

pinballlooking 02-06-14 05:01 PM

Quote:

Originally Posted by Mikesolar (Post 35530)
That is a good idea....the light switch. I may try that when i do another tankless that is a distance away from the master bath.

We have it that way for the two bath rooms bath and under kitchen sink light.

pinballlooking 02-23-14 08:33 PM

2 Attachment(s)
build.com sent me the wrong remote so I sent it back.
I found the remote I needed new on EBay for $70 shipped (best offer.) this was a better price.

For the long wiring I used phone cable. The phone guy had put in a temporary phone line until they could put it under ground. I asked if I could have the wire he said sure they would just toss in in the garbage anyway. So I put some of it to good use.

I now have control of my tankless hot water heater in my master bath room. We will bump up the hot water for showers then put it back down after the shower. This will be so much simpler than going out to the garage to adjust the temp then I forget to turn it back.


I got this Digital Inspection Camera for XMas. ($59.99 Black Friday)
Inspection Camera - Save on this Digital Inspection Camera
It worked great to help fish the wiring up through the wall. Since the shower is behind that wall it was very hard to fish the wire up through the wall but with this handy tool it was very easy.



http://ecorenovator.org/forum/attach...223_211533-jpg

pinballlooking 03-23-14 12:54 PM

My Condensate is plumed to a pex about 20’ at a downward slope. There are two weep holes at the hot water heater and when we shower or use a fair amount of hot water it is dripping out the weep holes.
Any suggestions how to fix this? Do I need to add a Tee with an air vent to this drain?
Is this to long for gravity feed?

Mikesolar 03-23-14 05:05 PM

The easiest thing to do is to have a drain from the heater loosely plug in larger tube so that there is an air gap before the 1/2" PEX tube. There is probably too much back pressure.

pinballlooking 03-23-14 06:04 PM

1 Attachment(s)
Thanks for your help.
Here is what I came up with to relive the backpressure. It is about 2' 3/4 Pvc then a clear piece of hose then the 1/2 Pex. I just tested it and it all seems to be good now.

I put a 4” piece of clear hose between the PVC and the Pex so I can see if it gets backedup.


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