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Old 04-17-2010, 12:52 AM   #1
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1960 26' Overlander
Everett , Washington
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Problem with PrecisionTemp RV-500 Install

I've been discussing this on another thread but this issue had evolved so considerably from the original post I thought I'd try to start a new thread.

Based on many favorable comments from respected members here such as Lewster and others, I purchased an RV-500 tankless water heater to replace the original Bowen in my 1960 Overlander. One of the many stated advantages of this unit is that it is supposed to be designed to fit the existing cut-out of the old heater.

My problem is that my Overlander has significant curvature in the lower hull where the water heater cut-out is located. When I position the RV-500 in the opening level on the floor with the top flange in contact with the hull, there is an approx. 1 1/2 inch gap between the bottom flange and the trailer skin due to the curvature in the hull. I don't know how to correct this AND keep the orientation of the RV-500 level. I'm attaching one pic that hopefully illustrates what I'm talking about (I do have a patch cut to trim out the larger opening for the Bowen to the smaller size of the RV-500 that is not shown in the photo.) Any ideas/suggestions very much appreciated as I'm currently stumped.
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Old 04-17-2010, 02:28 AM   #2
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When I replaced the original water heater in our '71 Tradewind, I shimmed the rearmost portion up by perhaps 7/8" or so to get the best possible fit. Is the R500 require level mounting?

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Old 04-17-2010, 06:56 AM   #3
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You can shim the bottom so the unit its flush. While I'm not an expert in the tankless model, I do know Airstream used that same solution with regular water heaters. Event he one in our '74 has a shim under it.
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Old 04-17-2010, 11:46 AM   #4
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I guess I was just assuming the unit had to be level. I checked the install paperwork again this morning and being level isn't mentioned. Thinking about your comments and the fact that everything in the unit (water and propane) is pressurized in a closed system, I guess it makes sense that level isn't a necessity. I have an inquiry into PrecisionTemp also, but you guys have made me feel SOOOOOOOOOO much better with your advice. Shimming is by far the easiest solution. I was seeing lots of aluminum fabrication in my future. Thanks very much!
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Old 04-19-2010, 09:47 AM   #5
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I will be interested to see what precision temp has to say about this. The burner in the RV 500 sits at the bottom of the copper enclosure and when it is fired up you can see the flame by looking in the small hole at the bottom. The fame is fairly low but intense and heats the water as it passes through the copper tubing. So being off level just a little may not effect its operation. Hope so any way.

Don
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Old 04-19-2010, 11:01 AM   #6
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if it needs to be level

Since you have to build a transition piece to bridge the gap between the existing opening and the smaller water heater flange, you could build a piece that has an outer flange that matches the curve of the trailer and an inner flange that is on a vertical plane. I would keep the unit flush at the bottom and inset along the top edge. To finish it off, you could then mount the exterior cover along the curve of the trailer.
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Old 04-19-2010, 01:00 PM   #7
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1960 26' Overlander
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Thanks for the suggestions, guys. I'm still uncertain about this, although leaning toward the shimming approach.

Don, your pictures from the other thread don't really show the bottom of the flange in the opening prior to trimming it all out. At least not from a side angle. Did you not have any gap at all? It looks like your Sovereign has some curvature to the hull, although not as much as my Overlander and your opening was smaller so maybe you didn't the fit issue.

Steve, thanks for your idea and I understand what you are getting at. I have two concerns. First, the RV-500 vents at the very top, along the entire top of the unit. I worry about the idea of recessing the top due to the venting. And, building a curved flange might be beyond my skill level. At least I have no idea how to do that.

I will post any recommendations I receive from Precision Temp. Hoping to hear from them soon. Thanks again.
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Old 04-19-2010, 02:23 PM   #8
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1960 26' Overlander
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Response from Precision Temp

Here is the (very prompt) response I received from Precision Temp:

Gary,

Any more than a 3 degrees tilt could present a performance problem. My concern is, depending on the degree of tilt, the flame could come in contact with the back side of the skirting on the heat exchanger although I have seen some pictures of the RV500 in some Air Streams that have more than the recommended tilt and the customer did not have any issue, performance or otherwise.

Gary Wulfmeyer
Service Manager/PrecisionTemp

I guess I'll have to put more thought into this. Maybe some kind of hybrid of both solutions (shimming slightly and retrimming the bottom and sides). Still pretty confused.

I do have to say, for what its worth to others, the people at Precision Temp have been wonderful. Very responsive to questions, know their product, and I would highly recommend them to anyone based on the service aspect.
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Old 01-14-2011, 01:38 AM   #9
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Precion Temp

Ya we bought a precion temp rv 500 about four years ago. Before you go any further I suggest that you return you're unit and purchase a small hot water heater. The RV 500 will never give you what you want. The unit is sensitive to ANYTHING that is a variable such as water flow rate it must be between 1.75 and 2.5 gallons per minute. Propane pressure and flow. You must make sure your manifold and propane lines and pressures are all correct. It is also sensitive to any dirt or debrise in the water lines. The lest bit of dirt will stop the impeller and flow. It is also sensitive to the degree of tilt. Further more if the power is at all different then optimal it will not work. Their are very few RV techs that can even begin to comprehend how the unit works let alone begin to trouble shoot one. Believe me I know what I am talking about. It probably works well in a lab but in real life it is a very expensive accessory that will never work correctly. And also our experiece with the company has demonstrated that they do not stand behind their product.
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Old 01-23-2011, 10:08 PM   #10
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how much room is behind the water heater? what about trimming the tabs back so it is still level, and make a fascia to "fill the gap". thus having a level install, and keeping the curvature the same on the skin
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Old 01-24-2011, 07:54 PM   #11
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Yep lifes and dance and if the wind blows too hard your precision temp will never work. Hope you filled out your warranty card.
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Old 01-24-2011, 08:12 PM   #12
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I agree with finch. Pull it back and fill the gap with sheet aluminum. You can then put a door attached to the exterior skin an nobody will be the wiser.
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Old 01-24-2011, 08:15 PM   #13
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Quote:
Originally Posted by steveer View Post
Ya we bought a precion temp rv 500 about four years ago. Before you go any further I suggest that you return you're unit and purchase a small hot water heater. The RV 500 will never give you what you want. The unit is sensitive to ANYTHING that is a variable such as water flow rate it must be between 1.75 and 2.5 gallons per minute. Propane pressure and flow. You must make sure your manifold and propane lines and pressures are all correct. It is also sensitive to any dirt or debrise in the water lines. The lest bit of dirt will stop the impeller and flow. It is also sensitive to the degree of tilt. Further more if the power is at all different then optimal it will not work. Their are very few RV techs that can even begin to comprehend how the unit works let alone begin to trouble shoot one. Believe me I know what I am talking about. It probably works well in a lab but in real life it is a very expensive accessory that will never work correctly. And also our experiece with the company has demonstrated that they do not stand behind their product.
Another perspective perhaps???????

I have used a Precision-Temp for 10 years in 2 different RV's (first in a 40' Monaco diesel pusher and then in my '06 19CCD Airstream) and never had so much as a burp from either unit. They were used off level, in high winds (I spend the summer in Hood River, OR....AKA the windsurfing capitol of North America= WINDY!!!) and never had a problem.

The above problems and sensitivities are all easily correctable with things like proper LP regulators (ALL LP appliances require proper LP pressure in an RV) and water filters (I ALWAYS use a sediment filter and a solid carbon block filer when connected to shore water). Plus, IIRC, the flow rate begins at 0.4 GPM and will continue to whatever flow rate you wish.

As with ALL tankless water heaters, each model has a designed-in degree of water temperature rise that is dependent on the water flow. I was running at least 2.0 GPM and never noticed a problem with the temperature of the water. Also, the temps of the ground water also play a big part in the output capacity of ANY tankless water heater. My new ride (listed below and pictured in my avatar) is getting an Aqua-Hot hydronic heating system which also generates endless, tankless hot water. This is a diesel-fired unit, though. They do now make an LP-fired unit, but they are more at home in very large trailers (5th wheels) and gas powered motor homes. Plus, they are a little pricey and large for installation in an Airstream.

I'm surprised that P/T never solved your problems with the unit.

Also be advised that I DO NOT WORK FOR PRECISION-TEMP! The preceding are my observations as a consumer/user of their product. YMMV (and obviously has).
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Old 01-25-2011, 12:28 AM   #14
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Ya well heres the story. We purchased it, we had a proffessional install it. We sent in the warranty. We were restoring the RV and when it was finished we started using it. At first we could only get luke warm water. I called old Gary and he said theres no way it could be the unit must be gas pressure. Said there were no techs here in WA to service it. So I install a new regulator and 1" gas line. Still only luke warm water 20 nminutes at a time so I call old Gary back he says check all the mixers in case there is back flow. So I check all the mixers. All good. Most of the plumbing is new. Then I call Gary back its now 16 months after the initilal purchase. Gary says it must be gas pressure. I get a second tech out he says toss it out get a hot water heater. So I payed that bill. I call Gary he says check GPM of water flow. Ya thats all good. Now we are 19 months into this deal. I finally find a tech that can work on the thing and he checks all my work and its all good. He changes a couple of sensors and it works. Every time I've called Gary I've asked him to man up and make it right. Just swap this one out for a new one and they can trouble shoot it in their shop. Gary says tough, no deal. So it works for another six months and craps out again. Bring the tech out another $400.00. Now I'm really pissed I get ahold of the owner. He and Gary get on the phone with me and they both tell me to take a hike. Six months later it craps out again. I'm into this thing over $3800.00 and it just quite again. The tech I have is really well qualified and fixes it every time. I am a heavy aircraft mechanic and no hack myself. Precision temp has never stood behind thier product with us and allways had plenty of advise which allways goes..."Ya it's not the unit so let me tell you how its allways something other then the unit." I have not purchased anything else to replace it cause they are the only game in town. I've heard other people say they are good. But these guys are so arrogant that they think they could never build a lemon. I am going to continue to tell any one who will listen. These guys did nothing for us and treated us like second rate citzens the whole way through.
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