kenmac
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Is this 3/4 line copper tubing ,or steel pipe ?
Experience with Tank-less water Heaters
- Thread starter Tractor Seabee
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Is this 3/4 line copper tubing ,or steel pipe ?
SirReal63
Platinum Member
The first 30' are the poly stuff the propane company uses, the rest is stainless corrugated gas line.
dstig1
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My Takagi is also a 199kBTU unit. It sits right next to the 2psi incoming natural gas regulator in our basement. Even for that short distance, I had to use 3/4" iron pipe for flow capacity, so yes you do need to watch that. I used soft copper with flare fittings for everything else, but I did not have a flare tool big enough for 7/8" soft copper (IIRC) that was required to meet the gas flow spec. Not the end of the world, but it is slower dealing with threaded pipe than bending some copper and flaring both ends.
In the summer time our gas bill is abut half the fixed monthly charge and half actual use (often under $20 total). We use gas for heat as well as for the cooktop, also. Ours is also ~97% efficient, IIRC. Condensing of course. I plumbed the condensate via PVC into the main drain stack (septic), and am not worried at all about it eating away the concrete tank. The volume of condensate is ridiculously trivial vs the total water output going into the tank. Sure it is acidic, but all those detergents you put down the drain are pretty basic, so it all evens out in the wash (no pun intended...)
In the summer time our gas bill is abut half the fixed monthly charge and half actual use (often under $20 total). We use gas for heat as well as for the cooktop, also. Ours is also ~97% efficient, IIRC. Condensing of course. I plumbed the condensate via PVC into the main drain stack (septic), and am not worried at all about it eating away the concrete tank. The volume of condensate is ridiculously trivial vs the total water output going into the tank. Sure it is acidic, but all those detergents you put down the drain are pretty basic, so it all evens out in the wash (no pun intended...)
Kentuckyfarmer
Gold Member
Straight from the rennai installation book. If vertical rise in the vent system exceeds 5 ft condensate collector must be used and if more than one elbow is used in the vertical section a collector must be used. As stated I don't have even a foot of vertical rise and just a little more than two feet total. Elbow on top and right out the wall. Also the reem 80 gallon water heater I had was rated at a little over 195,000 btu's. The tankless I bought is rated at 180,000 btu's. More than enough gas pressure and volume what I already had. I said most not all would have enough gas and probably most would be able to vent short enough not to require a condensate line. Lots of material on line full of facts and information.
It may not work out that easy for everyone but there are lots it will. As I stated earlier if vent is a problem there are outside units and no vent required. Also the tank type I had before just came on wide open, the tankless fireing rate is veried as stated by a previous poster. The proof in this house is in the pudding. In the summer months my gas bill was over 60 a month. Now it's under 20. The only thing that uses gas is the water heater in the summer. I'm not heating water all day every day. I'm only heating water when I need it. I can run hot water every day all day and not run out unless the gas got turned off or electric went out or heater broke and that can happen to anything. There is lots of options and some one with experience and expertise can make most applications work. There are about four things I notice different about having a tankless ver a tank water heater. Cheaper bill, always have hot water, no more big tank taking up real estate in the laundry room and it takes about 4 or 5 seconds longer to get the hot water to the faucet. And that I can live with.
It may not work out that easy for everyone but there are lots it will. As I stated earlier if vent is a problem there are outside units and no vent required. Also the tank type I had before just came on wide open, the tankless fireing rate is veried as stated by a previous poster. The proof in this house is in the pudding. In the summer months my gas bill was over 60 a month. Now it's under 20. The only thing that uses gas is the water heater in the summer. I'm not heating water all day every day. I'm only heating water when I need it. I can run hot water every day all day and not run out unless the gas got turned off or electric went out or heater broke and that can happen to anything. There is lots of options and some one with experience and expertise can make most applications work. There are about four things I notice different about having a tankless ver a tank water heater. Cheaper bill, always have hot water, no more big tank taking up real estate in the laundry room and it takes about 4 or 5 seconds longer to get the hot water to the faucet. And that I can live with.
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when looking at swapping out from 40gallon to tankless a few months back.
tankless water heaters = need a good installation. if there is a bad installation, and there can be problems. watch a couple hours worth of different youtube videos. of how to repair/fix issues, along with "bad install" videos. read through a handfull of different manuals, from same manufacture to different manufacture as far as installation goes for them.
valving and then fittings. (not including exhaust), can quickly cause a tankless water heater cost to sky rocket for initial purchase cost. and if room is not made during installation of valves and fittings, so you can physical remove stuff and put in new valves and fittings that will eventually fail. you are talking a higher repair bill. due to other stuff may need to be replaced just to replace a single valve. the large space for all the valves and fittings, can quickly take up space of what a tankless water heater uses.
yes they make valve packages and kits for tankless water heaters, to reduce space, but they come at additional cost.
=============
condensation line / drain line for exhaust vent, and properly running vent pipes can be a big deal. and make or break the overall installation of a unit as well.
just because you might be able to use say pvc pipe vs metal pipe. does not mean squat, if you are having issues of were you want to run the exhaust outlet / inlet pipe.
=============
natural gas / LP (liquid propane) gas.... pipe sizing for the gas needs to be sized correctly. from regulator on house to the tankless water heater, which good chance you may need to upside the pipe if you had a tank in there before.
you need your drip legs, shut off valves, and correct slops for the gas lines. or additional issues may come up.
=============
electrical 110v is needed for tankless, if you are still using natural gas / lp gas. to run the sensors and little computer board. this can be an additional cost if you need to higher an electrician. along with installing a switch for emergency shut off. if need be for the unit in close enough proximity to the unit.
==============
while the plumbing for a ventless tank, looks all simple enough. if not properly sized, correct slopes, correct material, correct spacing, correct solvents/glues, correct soldering, . the installation can go down hill quickly...
===============
if manual states to run say run some acid through system to clean it out a 1 to 2 or more times a year. that acid needs of course be "well ventilated", and most likely rather toxic. granted a tank water heater, you should pull drain on them and clean them out as well. but tankless water heaters less forgiving. than a tank hot water heater. and in that cleaning the crud out of them.
===============
and above still does not resolve some issues with tankless water heaters. were you can get (forget key word) a cold slug. were you are running hot water, and then unit turns off, for a moment, and you are still continue running hot water, then it turns back on. you could get a "cold shot" of water.
with above, i do not have a tankless water heater, and last example might be turning hot water on/off say washing/rinsing dishes. or cooking, or tankless water heater sized to large, or not enough "settings" to allow for a lower MIN. GPM of hot water to be had. as a result tankless hot water heater not kicking on. or switching between on/off causing hot,cold,hot,cold,hot,cold water coming through the hot water line.
=============
adding to above.
looking at spec's that i can remember. it almost seemed better to put in 2 smaller units. vs a single larger tankless water heater. so i could get the lower min GPM going. so the system would adjust to things better. vs having to BLAST really hot, hot water. to keep unit going. and/or setting a larger unit down in max tempature. to get by for the lower usage times of day when not a lot of hot water GPM wise was needed.
if cost was no object, i would be more inclined to install small little electric tankless hot water heaters, one at each sink, shower/bathtub, cloths washer. so if a unit went down you had backup at another sink or like, and you could size each one to given GPM of what was connected. would encourge going with a larger cold water line through home if did this. so there would be enough cold water supply and pressure to meet use.
tankless water heaters = need a good installation. if there is a bad installation, and there can be problems. watch a couple hours worth of different youtube videos. of how to repair/fix issues, along with "bad install" videos. read through a handfull of different manuals, from same manufacture to different manufacture as far as installation goes for them.
valving and then fittings. (not including exhaust), can quickly cause a tankless water heater cost to sky rocket for initial purchase cost. and if room is not made during installation of valves and fittings, so you can physical remove stuff and put in new valves and fittings that will eventually fail. you are talking a higher repair bill. due to other stuff may need to be replaced just to replace a single valve. the large space for all the valves and fittings, can quickly take up space of what a tankless water heater uses.
yes they make valve packages and kits for tankless water heaters, to reduce space, but they come at additional cost.
=============
condensation line / drain line for exhaust vent, and properly running vent pipes can be a big deal. and make or break the overall installation of a unit as well.
just because you might be able to use say pvc pipe vs metal pipe. does not mean squat, if you are having issues of were you want to run the exhaust outlet / inlet pipe.
=============
natural gas / LP (liquid propane) gas.... pipe sizing for the gas needs to be sized correctly. from regulator on house to the tankless water heater, which good chance you may need to upside the pipe if you had a tank in there before.
you need your drip legs, shut off valves, and correct slops for the gas lines. or additional issues may come up.
=============
electrical 110v is needed for tankless, if you are still using natural gas / lp gas. to run the sensors and little computer board. this can be an additional cost if you need to higher an electrician. along with installing a switch for emergency shut off. if need be for the unit in close enough proximity to the unit.
==============
while the plumbing for a ventless tank, looks all simple enough. if not properly sized, correct slopes, correct material, correct spacing, correct solvents/glues, correct soldering, . the installation can go down hill quickly...
===============
if manual states to run say run some acid through system to clean it out a 1 to 2 or more times a year. that acid needs of course be "well ventilated", and most likely rather toxic. granted a tank water heater, you should pull drain on them and clean them out as well. but tankless water heaters less forgiving. than a tank hot water heater. and in that cleaning the crud out of them.
===============
and above still does not resolve some issues with tankless water heaters. were you can get (forget key word) a cold slug. were you are running hot water, and then unit turns off, for a moment, and you are still continue running hot water, then it turns back on. you could get a "cold shot" of water.
with above, i do not have a tankless water heater, and last example might be turning hot water on/off say washing/rinsing dishes. or cooking, or tankless water heater sized to large, or not enough "settings" to allow for a lower MIN. GPM of hot water to be had. as a result tankless hot water heater not kicking on. or switching between on/off causing hot,cold,hot,cold,hot,cold water coming through the hot water line.
=============
adding to above.
looking at spec's that i can remember. it almost seemed better to put in 2 smaller units. vs a single larger tankless water heater. so i could get the lower min GPM going. so the system would adjust to things better. vs having to BLAST really hot, hot water. to keep unit going. and/or setting a larger unit down in max tempature. to get by for the lower usage times of day when not a lot of hot water GPM wise was needed.
if cost was no object, i would be more inclined to install small little electric tankless hot water heaters, one at each sink, shower/bathtub, cloths washer. so if a unit went down you had backup at another sink or like, and you could size each one to given GPM of what was connected. would encourge going with a larger cold water line through home if did this. so there would be enough cold water supply and pressure to meet use.
Last edited:
Kentuckyfarmer
Gold Member
I did commercial plumbing for 9 years and had another 11 years after that working on commercial boilers and natural gas distribution for a military installation. That said I think I have just a tad bit of experience and when I decided to change my water heater with a tankless I did the work myself. I bought all needed valves, pipe and tankless water heater for just a bit over 12 hundred. It's not rocket science or brain surgery to install one but if a person doesn't think it's possible to do it them selves there is plenty of capable folks out there that can do it properly. I have not had any problems at all and never experienced "cold slugs", condensation nor anything the skeptics of this thread have suggested. I don't know where you can come up with problems when you don't even have one to base it on. It's all up to the buyer to make sure it is installed right and capable installer is doing the work. Same as doing brakes on a car or removing your gallbladder. Just because he spent a night in a holiday inn doesn't mean they are qualified.
I was spectical of them years ago when I first seen them to be honest. About 6 years ago I had to replace my water heater in a place I sold. Was leaking. The person I knew for years and told me about his tried to get me at that time to replace it with a tankless. I bulked and bought a tank style. Bought this place a couple years ago and decided to talk to him again and give his the once over to see it up close and personal because the monster I had taking up about a third of my laundry room and looked like a third grader plumbed it and a first grader run the vent. It was a complete train wreck. After having this one problem free for two years I'm no more a skeptic and glad I went this route. Unless you own one and have experience using it I don't think you can honestly review it.
I was spectical of them years ago when I first seen them to be honest. About 6 years ago I had to replace my water heater in a place I sold. Was leaking. The person I knew for years and told me about his tried to get me at that time to replace it with a tankless. I bulked and bought a tank style. Bought this place a couple years ago and decided to talk to him again and give his the once over to see it up close and personal because the monster I had taking up about a third of my laundry room and looked like a third grader plumbed it and a first grader run the vent. It was a complete train wreck. After having this one problem free for two years I'm no more a skeptic and glad I went this route. Unless you own one and have experience using it I don't think you can honestly review it.
SirReal63
Platinum Member
I installed all three of mine, it was very easy since it was new construction that I framed, plumbed and electrified myself. The only help I got was from Rheem about gas line runs, that was a phone call. The main house has two outside units and the guest house has an inside unit. Outside units are the way to go here with our mild weather.
Raspy
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Kentucky,
I'm glad you've had such good performance from your system. And not having to upsize the gas line was a plus. I'm curious about the 80 gallon, 195,000 BTU water heater. That must have been a commercial unit.
Just to clarify a point. Condensing isn't something you might have or something you may experience. It is a design feature of any water heater over 85% efficiency. You either have a condensing unit or you don't.
The method used to get to 95% efficiency from 85% efficiency is to "condense" the combustion moisture out of the exhaust. This is called capturing the latent heat from the water vapor, or steam. That capture is worth 10% in efficiency and is achieved in modern water heaters and modern boilers by having an oversized and corrosion resistant heat exchanger. This means the fire is arranged such that the dripping does not affect it and the heat exchanger is made of high grade stainless steel. The liquid water produced, falls to a catchment system where it is separated from the fan forced flue gasses and is directed out of the heater to a drain system. So, it's not an accident, or something that might happen under certain circumstances. It is designed to continuously happen and it is the reason higher efficiency is possible. It is a completely different design than non-condensing.
Since you don't have experience with this type of combustion in yours it means yours is an earlier design that tops out at about 85% efficiency.
Cold slugs are when the water flow falls below the trigger point of the internal sensor in the heater. This happen when the water is not turned on all the way at the faucet, for instance. It can happen at single handled kitchen faucets where the user tries to lower the temp at the faucet by adjusting the handle more toward cold and accidentally shuts off the heater by lowering the flow rate through it. Or two faucets are running at the same time and one is shut off. This is more likely with a shower that has a modern restrictor or has become partially clogged over time. It can also happen on well systems where the pressure differential is set to wide on the pressure switch. If the flow slows enough, before the pump comes back on, the tankless can shut off while the water is still flowing, until the pump comes back on. The affect at the faucet is cold, hot, cold, hot. The reason this doesn't happen with a conventional water heater is that they don't care how slow the water flows. Any water flow is still hot.
Again, not trying to stop anyone from buying a tankless, or saying these things will ever be a problem. I know a lot of people really like them. I just prefer to have all the characteristics and costs and requirements out on the table, up front. And yes, I do have considerable experience.
I'm glad you've had such good performance from your system. And not having to upsize the gas line was a plus. I'm curious about the 80 gallon, 195,000 BTU water heater. That must have been a commercial unit.
Just to clarify a point. Condensing isn't something you might have or something you may experience. It is a design feature of any water heater over 85% efficiency. You either have a condensing unit or you don't.
The method used to get to 95% efficiency from 85% efficiency is to "condense" the combustion moisture out of the exhaust. This is called capturing the latent heat from the water vapor, or steam. That capture is worth 10% in efficiency and is achieved in modern water heaters and modern boilers by having an oversized and corrosion resistant heat exchanger. This means the fire is arranged such that the dripping does not affect it and the heat exchanger is made of high grade stainless steel. The liquid water produced, falls to a catchment system where it is separated from the fan forced flue gasses and is directed out of the heater to a drain system. So, it's not an accident, or something that might happen under certain circumstances. It is designed to continuously happen and it is the reason higher efficiency is possible. It is a completely different design than non-condensing.
Since you don't have experience with this type of combustion in yours it means yours is an earlier design that tops out at about 85% efficiency.
Cold slugs are when the water flow falls below the trigger point of the internal sensor in the heater. This happen when the water is not turned on all the way at the faucet, for instance. It can happen at single handled kitchen faucets where the user tries to lower the temp at the faucet by adjusting the handle more toward cold and accidentally shuts off the heater by lowering the flow rate through it. Or two faucets are running at the same time and one is shut off. This is more likely with a shower that has a modern restrictor or has become partially clogged over time. It can also happen on well systems where the pressure differential is set to wide on the pressure switch. If the flow slows enough, before the pump comes back on, the tankless can shut off while the water is still flowing, until the pump comes back on. The affect at the faucet is cold, hot, cold, hot. The reason this doesn't happen with a conventional water heater is that they don't care how slow the water flows. Any water flow is still hot.
Again, not trying to stop anyone from buying a tankless, or saying these things will ever be a problem. I know a lot of people really like them. I just prefer to have all the characteristics and costs and requirements out on the table, up front. And yes, I do have considerable experience.
