So I finally broke down and purchased and installed tonight one of the Precision temp Tankless water heaters. Good way to drop a quick grand, installation took about 3 hours total. Removing the old one was no problem but installing the new one was a little more involved. The inlet and outlets are just the opposite of tank heaters in that the hot water exits the bottom rather than a tank heater which exits at the top. So some re-plumbing was required along with  running some additonal propane line.

Now the good side, the hot water reaches the faucets in about the same time as a tank heater but the good thing is once you get the temperature adjusted you never have to re adjust and the hot water just keeps coming and coming. It is suppose to use less propane as it only runs when you are using hot water. It is very quiet and does not roar like our tank heater did when it came on. Another small feature is the weight is a savings as there is not 10 gallons of water to haul around. The flip side of that is there should no longer be an issue with the smelly water thing anymore so no more cleaning tank with vinegar and flushing. :) I really like that.

Hey Tab!

You sure are brave taking on a project like that in the deep snow of an Ohio winter!

Does the new system fit in the same space as the old HWH or did you have to enlarge the compartment you put it in?

Sounds like you did a great job on the install, now you'll have plenty of nice hot water to wash your hair in!

Best Regards!

Hey Paul, actually the unit is physically smaller than a 10 gallon heater but is made to fit in the spot of it so the flange is the same size. You have the option of a flush mount door or surface mount, problem with the flush mount you need to cut the hole bigger to recess the flange the door will fit in. So I went back to the surface mount as before. Pretty amazing how quiet it runs as you can not even tell it is on. You guys are not in the best of weather right now are you? :) Take care and see you on the road somewhere.

Sounds interesting.  Could you post a picture?

Keep us posted on your experiences with this. I started a short thread asking if anyone knew anything about these things quite a while back under another topic, and we have decided we really want one of these things, built in, when we buy (I am definitely NOT a plumber).

I can take a pic of the unit installed. It is an interesting little unit with a set of enclosed coils that the water runs thru. I am just amazed that it can heat the water that hot that quick. So many plus's to using one so far. May be a little more of a difficult thing when we get back to boondocking as if you shut the water off on the shower when you turn it back on you are eventually gonna get a shot of cold water, but I will work on the solution to that one

tmcblane: The solution to the shot of cold water might be to place an antibackflow (or check) valve in the hot line as close to the main shower valve as possible. What happens is there is slightly more resistance in the hot circuit (due to the heater) than the cold side and thus slightly lower pressure in the hot side. When you toggle the water off at the shower head a shot of cold pushes into the hot side thus giving you a shot of cold.  The check valve stops that cold push.

Dude, actually why the shot of cold water is because when you stop the flow of water it turns the burner off then when the flow reaches .4 gpm it kicks the burner back on. So that little bit of water in the unit gets pushed out before the burner comes back on. So far I haven't figured a way to defeat this problem. But you are right about the check valve, on a standard tank heater that will usually stop the problem. Thanks for the suggestion though, unfortunately it won't apply this time.

After I posted I thought about it more and realized exactly what you describe as the tankless (thankless?) military shower problem. Sorry about that.
How about installing a tiny (about 1 pint) accumulator in the hot line that might act as a miniature tank and maybe slightly dilute the cold burst??? I don't know what the temp rating of one might be though. Just a wild thought. I'd like to know what you come up with...

-- Edited by RVDude at 08:58, 2007-03-19

Good thought Dude, I will ponder that. :)

If .4  gpm is all that is needed to keep the flame on could you not crack a hot water valve in the kitchen sink prior to going in to take a shower?  That may keep the hwh fired up for the duration of your shower. Not very economical but none the less, a possible solution. 
 Flyone

Flyone, that is a thought and may actually be the answer although not using excessive water is the idea. Having said that I may be in a corner and just have to sacrifice and use the extra water. For those interested in the price, the actual price of the unit is $879, I bought the cold weather high wind option which adds $135 plus unfortunately for me the company is in my state so they got me for $70 tax plus shipping. :(

Tmcblanae,
Question?  Does the tank only use propane to heat or can it use electric also? I've seen the same type for the stick house and it is electric. I'm curious if they have the tanks that use both.

This one is propane only and I doubt that they make an electric one for rv's as the amp draw would be pretty high. Can't really use to much propane if you think about it as it is only running when you have the hot water valve on, so figure you take a 7 minute shower. That is nothing compared to how long the 10 gallon tank normally runs to reheat let alone running periodically thru the day to keep it hot. :) So far we are pleased but anything could arise and any time of course.

Hi:

I am interested in your reasoning as to why this is a good thing to do?

The weight savings is only about 80 lbs. for a 10 gallon water heater and at the present prices for propane it could take 20 years to eve break even on the dollars,  and if the old water heated had an electric capability it seems it would take forever to pay back.  Noise might have been an issue or perhaps the space savings, however it doesn't sound like the space saved is significant either.

Of course there is no better reason to spend your money than to get something you want!  In that case one doesn't even have to justify the expense. 

For me it is an issue of maintenace of the other tank with cleaning and the foul smell of the water. The propane use is not a real factor in the decision. Actually none of my reasons justify financially to change it out, it is more of a personal option. The weight is a factor for us as we are near our limit on GVW for the trailer. The noise is certainly an issue especially with ours being right outside our bedroom window and hearing that pop on in the middle of the night was a PITA. As far as space it could be smaller but it was manufactured to make it a direct replacement for the current water heaters used in the rv industry. As for the savings it is suppose to be upwards of 40% savings in propane. You would be a lifetime recovering the cost thru that avenue. Now for comfort it can not be beat, the water temp stays the same the entire you are in the shower so no adjusting for changing temp as you use the water out of the tank, you can take a shower as long as you want without running out of hot water and there is no waiting for recovery of hot water before the next person takes a shower. That is the big benefit for us.

I should post a note that can be a down side. Beings there is not standing water and the heater coming on at various times, if you plan on ever being where it will be cold you need to buy the weather package so the coils do not freeze.

Thanks for answering my question.  The constant supply of hot water is a definite plus! 

Here is another option that I did. Only about 400 with everything.
http://www.activeboard.com/forum.spark?forumID=91511&p=3&topicID=13558337

-- Edited by tchil at 12:50, 2007-09-20