Propane Tankless Water Heater (Home Use)

Make sure to verify the size of the gas or propane line required to allow the unit to function properly. I read that a dedicated 1" line was required.
 
Lazy Daze said:
This is fantastic information. I appreciate everything you've guys have written. I'm going to read through it a few more times.



I think I feel the same way as you. Once the water is hot... it's hot, right? Making a few assumptions, it sounds like maybe that plumber doesn't have much experience with the tankless heaters - sort of a "can't teach an old dog new tricks" kind of thing?
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That could be Dennis. I did put some time into the research because I put about another 1000 sq/ft on my house and my boiler was undersized to begin with. We talked about taking the indirect fired HW heater loop off and possibly being able to live with the Utica cast iron boiler I had (I have oil heat and was going to add propane). In the end I had too many variables and went with a new 5 section Peerless boiler with a Riello burner. This is obviously a different situation than you have.
The statement someone made earlier is still true for me though. Regardless of how strong my boiler is, I am still limited to 50 gallons of HW which is no problem except, when filling my jacuzzi tub. I still run out with that! :(
 
My original setup was a 115gallon electric Vaughn unit. This thing was a beast - it was super insulated and even lined on the inside with cement. Apparently this thing is a pretty high-end unit. But it's 25 years old and it had a small fire where some water dripped (very slowly) out of the upper element fitting and dripped onto the lower t-stat burning some wires. Nothing major and I could of rewired it and fixed the leak (the metal was still solid), but I took this as an opportunity to get something else. The only real problem was this happened about 2 hours before guests were coming over for my son's 8th birthday party. I flew over to Home Depot and bought the cheapest 30 gallon heater they had and quickly dropped it in - basically just something to "get us by" until we decided which direction to head with a new one.

So that's where we are now. If we went the conventional route, I think a 50 gallon unit would suffice for our needs, although I'd probably bump to a 70-ish gallon unit just to be safe. Twin tanks are an interesting idea. Actually, my forced-air heating is set up like that... Two 125-gallon Vaughn units that supply hot coolant to a copper coil inside the blower unit. Our electricity use is actually quite low - even when we had the 115 gallon HW in the mix - apparently these are quite efficient units. But seeing as it's 25 years old, even though it looked in good shape, figured it was time to make a change.
 
Over the past few years we have replaced our boiler and hot water heating method as well as renovating the three baths.

So a couple of observations; Plumbers in our area tend to make volume purchasing agreements with their suppliers, if you want something that a particular plumber does not "carry" you may not get pushback, but you will get a lot of negativity and reasons why it won't work (and how the standard package is better). Not to mention you won't get the best price. Obviously find someone who installs these on a regular basis.

In all of your calculations, sizing the water heater based on your family is a good start. But don't lose sight of the bigger picture and consider the capacity of hot water systems in similar houses in your area. Your current tank is 115 gallons. If that is the norm for similar sized houses, you might consider increasing your plan so as not to appear to have an undersized hot water system to a potential future buyer.

We don't have gas on our street, and the cost of bringing it in is ridiculous. We opted to go with a stainless steel tank on a separate zone from our oil boiler. If we had access to gas I'd convert in a heartbeat. A number of years ago I had a long term assignment in Europe, the flat we rented had gas fired on demand hot water, it worked great. I can only imagine that 20 years of progress has only improved the technology.

Henry




Sent from my iPad using Tapatalk HD
 
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Good points, Henry. You're probably right about your "observations", as well.

Just for clarification - I got rid of a 115g unit and replaced (temporarily) with a cheapie 30g unit. However, no one in my area has a 115g unit - most have 50g to 70g tanks. The person who owned my house 25 years ago worked for PPL (Electric Company) and had installed a super high efficiency unit.
 
Lazy Daze said:
My original setup was a 115gallon electric Vaughn unit. This thing was a beast - it was super insulated and even lined on the inside with cement. Apparently this thing is a pretty high-end unit. But it's 25 years old and it had a small fire where some water dripped (very slowly) out of the upper element fitting and dripped onto the lower t-stat burning some wires. Nothing major and I could of rewired it and fixed the leak (the metal was still solid), but I took this as an opportunity to get something else. The only real problem was this happened about 2 hours before guests were coming over for my son's 8th birthday party. I flew over to Home Depot and bought the cheapest 30 gallon heater they had and quickly dropped it in - basically just something to "get us by" until we decided which direction to head with a new one.

So that's where we are now. If we went the conventional route, I think a 50 gallon unit would suffice for our needs, although I'd probably bump to a 70-ish gallon unit just to be safe. Twin tanks are an interesting idea. Actually, my forced-air heating is set up like that... Two 125-gallon Vaughn units that supply hot coolant to a copper coil inside the blower unit. Our electricity use is actually quite low - even when we had the 115 gallon HW in the mix - apparently these are quite efficient units. But seeing as it's 25 years old, even though it looked in good shape, figured it was time to make a change.
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Understanding all the issues involved compared to what I'm used to - an older house, different market and product culture is a lot. What you've got going would be totally foreign here. We are all about gas tank style water heaters and gas forced air furnaces and conventional air conditioners. The one venture to newer technology we do see is a heat pump in lieu of an air conditioner. The public electric company here is a big proponent of heat pumps.

I'm not sure why I see so many dual 40 gallon gas units in my market vs. one 60 gallon or larger. I did check Home Depot's site, and they don't have much to choose from that is over 50 gallons. So, that may be the answer - the typical step up over 50 gallons in my market may be dual 40's. They usually sit side by side in basement locations. They typically go in 4-5 bedroom homes that have large master whirlpools. Another theory about dual 40's - I suppose you could shut one down if your needs for a period are minimal.

That 30 gallon you bought may have been a smart move if you need time to look at higher end solutions. I had a 25 year old air conditioner blow in hot weather in a rental I own, and the tenant was elderly. Guess who paid through the nose for rather deluxe (only thing in stock!) equipment in a rental? Oh well, the tenants have loved it - quiet and efficient.

In my market, assuming that 30 gallon is gas, I'd be very tempted to park a 40 or 50 next to your 30 and go with that. If tankless has become easier to install and service in my market, I'd look more closely at that. For the moment, I'm suddenly tempted to look into a basic 30 gallon unit to supplement my 50 - and make the whirlpool easier to use. Unless the kids go crazy in the shower (which they do) I only need the extra for the whirlpool - and could shut it down when I don't need it.
 
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Your not going to save any money on gas usage. You will have a pretty much endless supply of hot water. In a retrofit install it can become costly depending upon venting legnth and how close your gas source is. An average tank type water heater is about 36000 btu, one cubic foot of nat gas yeilds approx 1100 btu, the existing gas system in your home was sized to accomidate the demand at the time the house was built. You need to go back and see what you have and see what you need with the addition of 244,000 btus, thats about 240 cubic feet of fuel per hour that your system will need to make this heater work. You can not use the 1/2" line stubbed out for your existing tank type heater. Your existing vent won't work either. The other thing is the need to be descaled about every 6 months, not hard if your handy. If you are building a house I would say install a tankless and soft water. In an existing house I would go with what was originally installed or something similar where you could use your existing hookups. That's what I tell my customers.
 
stevea661 said:
..... In a retrofit install it can become costly depending upon venting legnth and how close your gas source is............... In an existing house I would go with what was originally installed or something similar where you could use your existing hookups. That's what I tell my customers.
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That is a good explanation and very sound advice. Great post!
 
We looked into it pretty carefully and it didn't work for us. The quotes I got were all +$4000 (local codes require a larger flue that was going to be a bear...among other things. Also, the length of the pipe to the showers was substantial for us and we either needed point of use units or stick with 40g units. Also, while it looked great for us thermally in the summer, when you were only raising water temperature 20-30 degrees, the winter of 50 degrees didn't seem nearly as promising. We opted for the super high efficiency 50g unit with a timed recirculation system so that we have instant on hot water at every faucet, every time. The unit is set to only operate when we need it (out of timer usage is just a normal delay) but the total savings in water and gas has been sufficient to pay for the system over a couple of years.
 
Steve, I currently have all electric, but I added a propane tank to run my garage heater and BBQ grill (which, as I understand, don't use much fuel) and also a small (4500W) generator which I wired into the house. The only problem with the genny is that it is only a 120V unit. I bought it based on talks with my wife that "it would be good enough to get through power outages w/o too much inconvenience). Well, after the first outage (Sandy) she says "You know, it would be nice if the generator could power the HW heater". Great... NOW she says that!

I really don't want to put money into a whole house, propane fired genny (to get the 240v I would need). So, the thought is to transition to either a tank or tankless propane HW heater.

Running the gas line shouldn't be too hard. I don't "think" the venting should be too hard... The basement is only 90% underground - I would be able to exit the basement wall at the top 1' (give or take). The vent would, however (given the current proposed location of the heater), have to travel about 3' to 5' along the wall to go from the heater to the exit point.
 
The heaters I use are Rinnai. My cost on a 9 gpm is about 1300.00, the venting for your install is about another 150.00. If you can exit your vent through a wall your outlet must terminate min of 4' bellow or horizontally from, nor less then 1' above any door, openable window, or gravity air inlet into the building (uniform plumbing code, check to see if this is what they use where you are). For the gas system the easiest stuff to use is a product like tract piping. The only hard part is tying into the existing gas piping system, ie steel pipe. Good luck.
 
Thanks, Steve. That's good info to be aware of. Do the window/door/etc restrictions stay the same for a normal tank exit? Or are the exhaust fumes lower enough that the req's change? I'll still check with local codes.
 
It's the same, check with your local building dept.
 
Dennis,

If you are still in the market, I found a DIY single point economy version online.






image_zpsb34031c6.jpg
 
That's a good one, Dave! I like it!

Still undecided between tank/tankless, but leaning towards tankless. My propane company is coming over Tuesday to give an estimate. I've been slowly gathering info on what I'd need to do it myself. Seems pretty straight forward, though. I could run the propane line and mount the tankless and run the venting - would just need the propane company to do the final "check for leaks".

dpmulvey said:
Dennis,

If you are still in the market, I found a DIY single point economy version online.






image_zpsb34031c6.jpg
Click to expand...
 
Make sure they give you an honest estimate on fuel usage with an upsized line heating water immediately vs. your current line heating stored water. The what is the B/E point? Just saying. Then again you have the hot tub so it may be sooner. Good luck. Post pix.
 
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Is there a reason why you could not use your existing hot water heater as a storage tank for hot water? Or is this overkill?
 
dpmulvey said:
Make sure they give you an honest estimate on fuel usage with an upsized line heating water immediately vs. your current line heating stored water. The what is the B/E point? Just saying. Then again you have the hot tub so it may be sooner. Good luck. Post pix.
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I don't have the hot tub - that was someone else in one of the posts. Currently I have electric, so I'm sure no matter which way I go with propane (tank or tankless), I should be better off. But, that's good idea... asking them about fuel usage.
 
Go Aweigh2452 said:
Is there a reason why you could not use your existing hot water heater as a storage tank for hot water? Or is this overkill?
Click to expand...

I had planned on just selling off the little electric tank heater on Craigslist (it's less than a year old). But that's an interesting idea about keeping it and using it as a slave tank. Got to think more about that.
 
Don't bother, if you want a long explanation I could do that, But............................................... :)
 
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