Tankless Water Heater

RVMichael · 07-28-2018, 02:22 PM

Help! I have been trying to use my tankless water heater, but so far all I get is extreme "sandwiches". I even tried turning it down to 99 degrees and watched the temperature go right up to 116 degrees. I've searched for the sweet spot, but so far only those extreme sandwiches. Wife is really starting to dislike which could threaten longer trips.

Laco · 07-28-2018, 03:13 PM

Check input water pressure. You need between 50 - 55 PSI for that heater to work correctly. I had to put an adjustable pressure regulator on mine, set to 53PSI to get my water heater to work, which it does now.

Bob Denman · 07-28-2018, 03:32 PM

I'm using 50 psi, and all is good!
Question: Are you trying to mix your hot & cold water; in order to make for a comfy shower? It's actually best to just the the temperature where you want it to be, and only use the hot water.
We tinkered around in here with a bit of a poll: most folks seem to be in the 105, to 110 range...

mark4Jesus · 07-28-2018, 11:00 PM

On this trip we just got home from, ours was doing similar to the OP's unit. Had water pressure set to 48. May bump it up next trip and see how it works. Then again, may do it in the driveway and try it!

Diemaster · 07-29-2018, 12:09 AM

is this 50-55 psi a "general rule" for tank-less heaters? i got a fixed regulator after reading the high psi could cause pipe bursting water damage. i just tried in my "campsite" (driveway) and i have hot water if the water pump is on. if it's not running, and on the city water, no hot water.

ordered a adjustable one on amazon so we shall see...

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Bob Denman · 07-29-2018, 12:20 AM

I just went with a simple 50 psi "fixed" one...

Laco · 07-29-2018, 01:24 AM

Typically the fixed pressure regulators are less expensive and are not all that accurate. You should be able to get up to 60PSI without creating plumbing problems, it says here in fine print. The conservative approach is to not go higher than 55psi. Somewhere buried in the Girard documentation, or they told me, you need a minimum of 50psi, hence the recommendation to set your adjustable regulator between 50 and 55. I was about ready to pull the tankless and put a regular water heater in, then read that about pressure, dumped my cheap fixed regulator, went with an adjustable set to 53psi, and the heater works great now. We have no problems mixing hot and cold water for the temp we want for things like the shower. I set the temp for 118 to 120 degrees, and frankly am pleased with how it works.

mark4Jesus · 07-29-2018, 02:31 AM

Quote:

Originally Posted by Laco

Typically the fixed pressure regulators are less expensive and are not all that accurate. You should be able to get up to 60PSI without creating plumbing problems, it says here in fine print. The conservative approach is to not go higher than 55psi. Somewhere buried in the Girard documentation, or they told me, you need a minimum of 50psi, hence the recommendation to set your adjustable regulator between 50 and 55. I was about ready to pull the tankless and put a regular water heater in, then read that about pressure, dumped my cheap fixed regulator, went with an adjustable set to 53psi, and the heater works great now. We have no problems mixing hot and cold water for the temp we want for things like the shower. I set the temp for 118 to 120 degrees, and frankly am pleased with how it works.

I have an adjustable so I will set it to 53 as you did and give it a try, thanks much!

chad523 · 07-30-2018, 05:55 PM

Good information, been trying to get mine to work, if I turn the water pump on it work soso, will try increasing pressure, hope it works, thank you

Bob Denman · 07-30-2018, 06:47 PM

Good luck!

We want to keep the showers working: we might end up in a site that's downwind from you...

The Gritz Carlton · 07-30-2018, 07:04 PM

I think tankless water heaters in RV's is the result of a good product salesperson to the buyers of the RV manufacturers. They are not meant for this application...otherwise, there would not be so many threads on the subject or so many modifications to make them work just soso. This is one of the 3 reasons I chose the Chateau over the Dynamax. When you have to re-engineer a product to work as designed...not good.

Diemaster · 07-31-2018, 06:29 AM

fixed. water pump off. dry water tank. connected city (shore) water with adjustable regulator set to 52/53/ and water heater worked like a charm

thanks for the advice

Bob Denman · 07-31-2018, 12:05 PM

Congratulations!

Gritz,
I think that the number of threads about them has more to do with the fact that it's something that we're all still learning about...

Once you've got them figured out: they seem to be pretty nice!

bevedfelker · 07-31-2018, 01:27 PM

Unless you've researched and read about the tankless water heater it is easy to assume it works just like any other tanked water heater.

First misconception is that like a regular water heater you regulate temperature of the water coming out of the shower by adding or subtracting cold water with the cold water valve. You regulate the water temperature by setting the temperature on the thermostat for the tankless water heater -- and leave the cold water tap alone.

Water pressure is extremely important to the proper operation of the tankless on demand water heater. As described above -- the sweet spot for proper water heating is 52-53 psi. You need an adjustable water pressure regulator so that you can adjust the water pressure. A fixed water pressure regulator will not be good enough.

The Gritz Carlton · 07-31-2018, 02:05 PM

We have a beach house in PCB that sits a lot, unattended. I use a window A/C with a stand type fan to circulate air around when we're not there. It keeps humidity down and saves having to leave the central unit going all the time which cuts the cost of power by 75% minimum. Once there I let the big boy blow and go! I used to turn the conventional water heater off also, saving power as it didn't just cycle on and off for weeks at a time. I recently replaced the water heater with an on demand unit...works great in a fixed residence where volume of water is not a concern. I still have the conventional unit hooked up where I can switch back and forth if needed. My only negative towards the tankless in an RV is the volume of water it requires to maintain effectiveness. Seems you have to leave the water going during a shower to keep steady temperature. We dry camp a lot so water conservation is tops on the list. With varying pressures and temperatures of water at CG's, doesn't this pose a constant adjustment issue? Nothing worse than the cold/hot/cold/hot shower. Also, don't you use at least twice the water per shower vs. the conventional water heater?

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