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Precision Temp RV500 Review – Tankless Hot Water Heater

For a long time I have recommended the RV-500 Tankless Hot Water Heater from Precision Temp, but recently I found myself no longer being able to recommend it.   I don’t normally do product reviews, but the RV500 is one of those appliances that a lot of tiny housers use and people wanting to build are planning on installing.  So I thought I’d share my experience here.

tankless-rv500-review

To be transparent, I owned the RV550, which is very similar to the 500, the only difference is the 550 vents out the bottom via a pipe, where the 500 vents out a side panel.  While there are technical differences, they’re almost identical, save the vent method.  Most people don’t know about the 550 as its just a product variant, it’s fair to say its the same series, hence me reviewing this under the RV500 title because that’s what most people will search.

So to the review.

I purchased the unit in 2013 after doing a lot of research about the unit.  It seemed like my options where this unit or an Atwood variant that honestly didn’t look that great as an option.  I laid down the $1100 for the unit (gulp) and awaited it’s arrival.  In addition to the unit I purchased the 110V to 12V adapter, which let’s you simply plug in the unit to a standard power outlet.

When the unit arrived I was checking it out when I noticed an odd noise when picked the unit up.  At first I thought it was just a check valve or some wires jiggling, but upon further listening I became concerned.  I decided to crack open my brand new unit and I’m very glad I did.  What I found was one of the main vent hoses had come loose and the hose clamp was rattling around in the bottom of the unit.

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I realized that this was a pretty serious thing, because if I hadn’t investigate and just installed, it would have mean that the vent would be pushing exhaust into the interior of my house.  Very dangerous.  As a side note I later got a new unit and looking at how firmly that vent host was attached, I’m guessing that it was never connected in the first place, not just wiggled off in shipping.

It was then I asked for a replacement unit because I wasn’t sure I could fix it, plus it was brand new out of the box.  I put it right back in the box, repacking just like they sent it to me.  Called them and they sent me a new one and asked for me to send it back, the customer service was good on that call.

wrong

What wasn’t good, was later on, when they received the unit back; one of their staff sent a snide email telling me how there was nothing wrong with the unit and how scratched the unit was.  He then began telling me how I was wrong because they “test every unit before it goes out.”  The unit would have worked fine even if they test it, it just was not venting out the vent tube.  Keep in mind I sent it in the exact packaging they sent it to me in.

The email was rude, the email was petty, but more concerning was that as a layman I could figure out that the unit was not assembled correctly, but the person working for the company didn’t notice a 4 inch vent hose being so loose it wasn’t seated on the connector at all.  I was annoyed by the person’s unprofessional behavior, but ultimately I realized I had a working unit and that’s all that mattered.

I got my new unit and I immediately opened it up to check the internals, all looked in order.  I then installed the unit in my house a while later.  I had a professional plumber come in and install it because I don’t like messing with gas lines.  The install went smoothly until we had to turn the thing on.  The unit would start working, but the vent fan wouldn’t kick on.  Later on we were able to get the vent fan working, but it wouldn’t light.  Finally I gave Precision Temp a call after going round and round, he told me to un-ground the unit by disconnecting the green wire.  The unit turned on and worked instantly.

wiring

This really frustrated me because as you can see above – this is a screen shot from the install manual – you’re supposed to ground the unit.  The support person said that 12 volt is very sensitive so if it’s grounded, it can cause trouble.  This is all true, but their install guide says green goes to ground.  In the end, I didn’t care too much, I had hot water and it was great to have hot showers.

Later that year winter came and I was finding that even in the mild winters of North Carolina, the unit couldn’t get the water hot enough for my showers.  It would be solidly warm, but never hot.  I really like hot showers, one of the best things on earth, so this was disappointing.  I tempered this with the fact that the unit could only rise the water temperature so much, it was rated at around 55,000 btu and that inherently can only warm cold water so much.

I really did like how efficient the unit was, using a 20lb propane tank (like you have on your grill) I could have hot showers and cook meals on my gas range for around 4 months per tank!  That was really nice, I bought four tanks and that would allow me to shower and cook for an entire year, plus have one extra.  This meant my gas cost was $4.50 per month!

Then it all went to hell.

I was taking a shower about a month ago and once I was done, I stepped out to towel off.  I noticed that the tankless didn’t turn off, but instead kept the burner going.  I turned the water back on to see if I could trigger it to turn off, nothing.  Tried the sink, nothing.  I unplugged it, nothing.

What I didn’t know was that the safety pressure release valve had failed and the unit was building steam pressure, all a sudden the unit tore itself apart.  The unit had built up so much steam pressure that it literally ruptured the wall of one valves and tore the threads out of another.  It scared me half to death, but luckily all the steam and debris was kept within the case when it exploded.

rv500-valve-bad

Water began to pour out of the unit, propane began to bubble through into my house, in a few seconds my floor was covered with water and the air was thick with propane.  I ran outside and turned off the water and the gas.  When I turned back water was dripping out of my house from all corners.

I let the gas vent out and then I got to mopping.  This was the last straw for me, what if I hadn’t been home, the water would have flooded my entire house for hours!  What if I had pulled off the cover to inspect it with my face right there as it ruptured!

I cleaned up and called a plumber and schedule an appointment to have a different brand to be installed, I was done with the Precision Temp tankless hot water heater.  I’ll do a post soon about what I opted for in it’s place.

Final thoughts:

In my opinion the unit is way more expensive than it should be.  I was able to get a new unit for around $600 and it has three times the btu and a similarly compact vent system.

I have personally seen two manufacturing failures on two different units.  One faulty unit might be bad luck, getting two faulty units points to a larger issue in their standards and at $1100 a piece, their standards should be high.  Obviously not.

Having a safety valve fail is a really big deal.

Your Turn!

  • How are you planning to heat your water in your tiny house?
4 Comments
  1. I plan on using a Rheem 20-gal electric water heater under the counter in the kitchen. I am NOT messing with propane for the experience you had. Talk about ka-boom your house to pieces, not to mention it will destroy your lungs in the explosion, and you’re left dying from the butterfly effect on your lungs (people bombed in air-tight buses die the same way), even if nothing else happens to you. Plus I have not had good experiences with in-line heaters. They seem fickle and don’t know when to supply hot water. I’ve had one in someone’s house not deliver hot water when doing a weeks dishes for the owner. No thanks. I’ve NEVER had this experience with a traditional water heater. Go down to a 10-gallon if you need it and use a shower head with a RV-style cut-off valve. I do just fine on an RV 5-gal water heater in my travel trailer, my current house while I’m SLOWLYYY finishing the inside of my tiny cabin.

  2. Whoa, Ryan…scary as heck and much appreciated! I hadn’t yet decided on a brand but this one was on my list so now it’s off. I still like the idea of a tankless but I’m taking Stephanie’s advice to heart and will hook up an electric version. I love TH peeps for their willingness to share their wisdom. Thank you!

  3. Yet again another reason why I ditched the tankless unit I had and bought a Noritz NR501-OD-LP from a local dealer—$626.78 and had a professional plumbing company experienced with tankless water heaters of all kinds install it, test it, set it up, blah, blah, blah. And will come out to service it or repair it if I ever need them to do so.

  4. Are there any other units that vent through the floor like this one?

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