Furrion On-Demand Water Heater

Ruggybuggy

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To those that have the Furion on demand water heaters. Are you getting a cold water shot after you turn the water off them back on in the shower when you’re trying to conserve water while boondocking? The Furrion has a device on the back of the heater that is supposed to eliminate this problem.
 

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Maybe I should explain further. I just purchased a 2025 22RK a couple of weeks ago and the dealer is keeping it in storage until spring. I have not used the Furrion on-demand water heater and this is my first on-demand heater. Everything I have read is that the characteristics of the on demand system is that when you shut the water off (military shower when boondocking) the heater will shut off. When you turn the water back on it takes a couple of seconds for the heater to cycle on so you will get a cold water blast. The Furrion uses a device on the back that mitigates or hopefully eliminates this problem. The only other on-demand water heater I know that eliminates the cold water blast is the Tru-Flo water heater.
 
The water in the line will cool depending on the distance from the heater and how long it is off.
 
Interesting, thanks for confirming. Do you know if the Furrion heater has freeze protection?
Furrion has a revised motherboard with "freeze protection" that should be verified and/or installed. I bought mine from Lippert for like $105 and installed it myself on my 2022. Works great.

Part of reducing the cold shots of water is user training such as using only hot water vs a mix and etc.
 
Furrion has a revised motherboard with "freeze protection" that should be verified and/or installed. I bought mine from Lippert for like $105 and installed it myself on my 2022. Works great.

Part of reducing the cold shots of water is user training such as using only hot water vs a mix and etc.
If you set the temperature and use only the hot water tap does it eliminate cold water shots when the turning off the water then back on?
 
If you set the temperature and use only the hot water tap does it eliminate cold water shots when the turning off the water then back on?
Here's what we do that works for us. We only use the hot water and set it to like 115*. I have replaced the standard shower head with the oxygenetics model that's more low flow for boondocking. We then let the water trickle out of the shower head while we are soaping up so that the water heater burner never really shuts off. If you do that, it works great. If you allow the burner to shut off, there will be a burst of cold water in the lines. There are lots of lovers and haters of the new on-demand water heater systems. The Furrion does not really have a recirculation feature that keeps the water circulating in the back ground to eliminate the cold bursts. The process we use manages them and keeps them to a minimum. We've been using it for two seasons now and have a battle rhythm that works. We only boondock with our on-board water tank and are never camping at parks or places with full hookups. Good luck. Others can chime on what works for them.
 
Here's what we do that works for us. We only use the hot water and set it to like 115*. I have replaced the standard shower head with the oxygenetics model that's more low flow for boondocking. We then let the water trickle out of the shower head while we are soaping up so that the water heater burner never really shuts off. If you do that, it works great. If you allow the burner to shut off, there will be a burst of cold water in the lines. There are lots of lovers and haters of the new on-demand water heater systems. The Furrion does not really have a recirculation feature that keeps the water circulating in the back ground to eliminate the cold bursts. The process we use manages them and keeps them to a minimum. We've been using it for two seasons now and have a battle rhythm that works. We only boondock with our on-board water tank and are never camping at parks or places with full hookups. Good luck. Others can chime on what works for them.
Thanks for the reply. I think what I’m going to do is to add a water miser. Using your procedure I can recirculate the water back to the fresh water when first starting the shower until warm. After the water is off I can again recycle the first bit of cold out then send water back to the shower head. Thanks for the reply.
 
To those that have the Furion on demand water heaters. Are you getting a cold water shot after you turn the water off them back on in the shower when you’re trying to conserve water while boondocking? The Furrion has a device on the back of the heater that is supposed to eliminate this problem.
The mixing tank usually does a great job of dampening the temporary fluctuations in temperature. However it doesn't do as well at dampening the "cold water sandwich" as it's called in tankless circles. If you turn off the flow of water, it turns off the tankless and puts out the flame, then it has to purge the exhaust gases from the flue. When you turn it back on, it may have to complete the purge cycle, if it hasn't already, before starting up again from scratch.

During start up, it has to determine the incoming cold water temp to calculate how many BTUs to produce to make up the difference between set-point and inlet water temp at the rate of speed it is traveling through your pipes.

While it's figuring that out, it also has to "prove flame" to make sure it isn't passing unlit gas into the flue. Once flame is proved, propane is allowed to flow and the flame is dialed in to produce just the right amount of heat to bring the cold water to your set-point at whatever rate of flow the water is traveling.

In the meantime, cold water is passing through the tankless, unheated, on its way to your back!! In front of that slug is the water that was heated on your last rinse and is still sitting in the pipes (albeit a little cooler, but not COLD!). Warm in the front, cold in the middle, hot at the end. Cold Water Sandwich.

The onboard computer chip of your tankless is WAY FAST at calculating all that stuff, it ain't fast enough to eliminate that WOO-HOO cold shot that got past the equipment.

In short, your tankless is working as it should. Also, the advice of those here who change the set-point to a hot-water-only temperature are right on the money for insuring comfort, but even their advice won't prevent the cold water slug from happening if you decide to turn off the faucet to conserve water. No flow? No flame and no heat.

Step aside for that one little second to let the cold slug pass, then enjoy precise and endless hot water until shut it off again.

If you have a ready source of incoming water and an outside hot/cold water fixture (and current outdoor temps are acceptable to you), fashion yourself an outdoor shower enclosure and you can forget about having to dump at all.

Hope that helps.
 
The mixing tank usually does a great job of dampening the temporary fluctuations in temperature. However it doesn't do as well at dampening the "cold water sandwich" as it's called in tankless circles. If you turn off the flow of water, it turns off the tankless and puts out the flame, then it has to purge the exhaust gases from the flue. When you turn it back on, it may have to complete the purge cycle, if it hasn't already, before starting up again from scratch.

During start up, it has to determine the incoming cold water temp to calculate how many BTUs to produce to make up the difference between set-point and inlet water temp at the rate of speed it is traveling through your pipes.

While it's figuring that out, it also has to "prove flame" to make sure it isn't passing unlit gas into the flue. Once flame is proved, propane is allowed to flow and the flame is dialed in to produce just the right amount of heat to bring the cold water to your set-point at whatever rate of flow the water is traveling.

In the meantime, cold water is passing through the tankless, unheated, on its way to your back!! In front of that slug is the water that was heated on your last rinse and is still sitting in the pipes (albeit a little cooler, but not COLD!). Warm in the front, cold in the middle, hot at the end. Cold Water Sandwich.

The onboard computer chip of your tankless is WAY FAST at calculating all that stuff, it ain't fast enough to eliminate that WOO-HOO cold shot that got past the equipment.

In short, your tankless is working as it should. Also, the advice of those here who change the set-point to a hot-water-only temperature are right on the money for insuring comfort, but even their advice won't prevent the cold water slug from happening if you decide to turn off the faucet to conserve water. No flow? No flame and no heat.

Step aside for that one little second to let the cold slug pass, then enjoy precise and endless hot water until shut it off again.

If you have a ready source of incoming water and an outside hot/cold water fixture (and current outdoor temps are acceptable to you), fashion yourself an outdoor shower enclosure and you can forget about having to dump at all.

Hope that helps.
Thanks for the info, very informative. I think I’ll install a water miser. That way when I turn on the water back on, I can have the water miser routing the water back to the fresh water tank. Give it ten seconds then flip the miser back off and send the water to the shower head and avoiding the cold water sandwich and save my water while boondocking.
 
Thanks for the info, very informative. I think I’ll install a water miser. That way when I turn on the water back on, I can have the water miser routing the water back to the fresh water tank. Give it ten seconds then flip the miser back off and send the water to the shower head and avoiding the cold water sandwich and save my water while boondocking.
I'm not sure how a water miser works, but if it allows flow to continue through the water heater, that will cure it. GPM flow is important - more is better in this case. There is a lower threshold of flow that is required to keep the heat exchanger from overheating. The minimum flame produces a certain # of BTUs that need to be carried away. The circuitry won't allow it to overheat, but if the flow isn't high enough, the flame will pause to protect the heat exchanger. I'm not sure what that flow rate is for the Furrion, but now I'm curious enough to look it up (if it can be found - it's not usually a ready piece of info).
 
I'm not sure how a water miser works, but if it allows flow to continue through the water heater, that will cure it. GPM flow is important - more is better in this case. There is a lower threshold of flow that is required to keep the heat exchanger from overheating. The minimum flame produces a certain # of BTUs that need to be carried away. The circuitry won't allow it to overheat, but if the flow isn't high enough, the flame will pause to protect the heat exchanger. I'm not sure what that flow rate is for the Furrion, but now I'm curious enough to look it up (if it can be found - it's not usually a ready piece of info).
Found it: "IMPORTANT! For proper operation, this water heater requires a minimum water flow of . 80 Gallon per Minute (GPM) for each Hot Water faucet it supplies."

Make sure the water miser produces a flow rate that meets or exceeds 0.8 gallons per minute so the flame will stay lit.

Be advised: You'll be pumping hot water into your fresh water tank. I'm not sure that's a good idea. If it were me, I'd just step aside to let the cold water slug pass by. ;)
 
Found it: "IMPORTANT! For proper operation, this water heater requires a minimum water flow of . 80 Gallon per Minute (GPM) for each Hot Water faucet it supplies."

Make sure the water miser produces a flow rate that meets or exceeds 0.8 gallons per minute so the flame will stay lit.

Be advised: You'll be pumping hot water into your fresh water tank. I'm not sure that's a good idea. If it were me, I'd just step aside to let the cold water slug pass by. ;)

My other trailer had a water miser and yes it does send some hot water back to the fresh water tank but it’s only for a couple of seconds so it really doesn’t change to temp of the fresh water.
 
To those that have the Furion on demand water heaters. Are you getting a cold water shot after you turn the water off them back on in the shower when you’re trying to conserve water while boondocking? The Furrion has a device on the back of the heater that is supposed to eliminate this problem.
We have installed the Shower Miser and the Sink Miser and both work beautifully. No wasted water, no filling up the gray tank unnecessarily, and no cold blast.
 
We have installed the Shower Miser and the Sink Miser and both work beautifully. No wasted water, no filling up the gray tank unnecessarily, and no cold blast.

Which shower miser did you go with? Do you have a link to the one you purchased? Thanks
 
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