Tankless Hot Water Heater

[Kcass]

Hi There-
Anyone out there with a tankless hot water heater? We are having issues where only the bathroom sink will activate the hot water. (The shower will get hot only after we turn the bathroom sink on). Any ideas on what the problem could be? Thanks in advance for any advice.

Kari

[taylorbob1]

IMO…
There’s not enough flow coming from heater to the shower to activate/turn-on the Hot Water Heater. That is, you have already diagnosed the problem by turning-on another faucet which allows the heater to function.

- Check for blockage at shower head (debris?)
- Try removing shower head, see if enough comes thru to activate heater
- Finally, there is a valve on the heater that can be adjusted to increase flow (IIRC, several threads on this subject. Use the SEARCH function)

[chunker21]

As discussed these things require significant water flow rate to activate the water heater. When checking the shower head for debris, also see if you can enlarge the water restrictor so you get more flow. I.e. drill it out or remove it.

[wrapped]

If you're hooked to city water supply try turning your water pump on also.

[DavidEM]

I had the same problem with my shower. I removed the little white button restrictor which is in the connection between the hose to the head and it works fine now.

David

[RCS]

I had the same problem with my tankless water heater. Two things solved the problem for me, One, I removed a lot of plastic bits from all the faucets heads by taking off the aerator head and ran water through the lines (looked like bits from a drill came out) and two, make sure your water pressure is at least 50 psi. If the pressure is too low, it will not activate the heater. Also, on a semi-related issue, if you get an E-1 error on the water heater display, check to make sure your propane is on (don't ask how I know about this one!)

[taylorbob1]

Here’s a good bit of info on Tankless Water Heater taken from another thread.
Most of it is probably relevant for your coach.
Thank you “Judge”

“2) Girard Tankless Water Heater:

I have had a Girard GSWH-2 in my last two coaches and we love them. We can take a hot shower for 30 minutes is we want. The key is knowing how to properly use them.

1) Water flow is key. You need 40 - 45 PSI minimum and 55 PSI of pressure is optimal.

2) You need to remove all your strainer / filters at the faucets and clean them of contruction and other debris that limit flow. Most people don't realize how much debris is in the faucet strainer / filters that are restricting flow.

- There is also a strainer / filter at the water inlet on the back of the garage. You need to check that one as well but it may be harder to get to depending on the design of your coach.

3) Only use hot water.... DO NOT MIX cold water. You set the desired tempeature you want and it will keep the water at that temperature. My wife likes 108 and I like 105. We set the temperature, turn on the hot water and take a shower for as long as we want. When she is washing dishes she sets it to 115.

4) Do not run another faucet (or flush the toilet) when using hot water at another faucet. Again, it is all about proper flow. RV's are not like your home that has plenty of pressure to keep flow contstant with multiple faucets in use at the same time.

5) The water flow control on the back of the unit should basically be wide open. However, if camping in colder temps and climates, slowing the flow can help when ground water or tank water temps are very cold. If the flow is too fast, the water does not spend enough time in the heat exchanger to get fully hot.

We have full hook-ups 90% of the time so water usage is not an issue to us. If someone does a lot of dry camping, then a traditional hot water tank heater is more suitable. Otherwise, we have have not had any real complaints with the Girard Tankless.

I also recommend changing faucets from a single control to dual control faucets. The single cartridge in the cheap faucets used in RV's can sometimes leak and allow cold water to mix with the hot water.

I replaced my shower control from a dual to a single so when I turn on the hot, there can only be hot water. I also replaced the bathroom and outdoor kitchen faucets as well to dual controls with a high arch moveable spout.”

[Kcass]

Thank-you Everyone! Great information, we appreciate the help!!

[JONJON]

I suggest you focus on TaylorBob1's number #3. It is not intuitive to someone who has always had "tanked" hot water to turn the hot valve on all the way and leave it there. Your temperature is regulated by the thermostat on the wall that controls water temperature. If you are mixing hot and cold water to attempt to obtain your favorite temperature, it will never get there. I see that your post was a few weeks back, so hopefully you have resolved your issues by now.

[45 year RVr]

I had the same issue on my 2021 Miramar. I found there is a restrictor in the flexible hose from the control valve to the shower head. If you put the hose on backwards it will actually work. I stopped into Lowe's and bought a replacement hose for $12. Problem solved.

[danl61]

Originally Posted by Kcass

Hi There-
Anyone out there with a tankless hot water heater? We are having issues where only the bathroom sink will activate the hot water. (The shower will get hot only after we turn the bathroom sink on). Any ideas on what the problem could be? Thanks in advance for any advice.

Kari

Friends of ours have a tankless water heater and have a similar problem. Turns out they were connected to the park water source and the supply was just not enough to keep the heater working. The fix was pretty easy though, they filled their fresh water tank and used the pump instead.

[chuckb]

check the outside shower water valves, if the showerhead is closed, (the little button on the side of the showerhead) and the water valves (hot and cold) are open water will circulate and cause a pressure issue, I had this problem and could not get hot water in the rear bath, it cost me a few hundred bucks because the factory ensured me it was the main circuit board was bad.