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Small Cabin Forum / Off-Grid Living / Instant water heater and a mixing valve
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sparky30_06
Member
# Posted: 22 May 2018 07:33
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OK so finally got some temp water hooked up at my shack and tested out my shower set up. I'm using an Eccotemp L10. In my shower I have one ball valve for the hot water and one ball valve for the cold. Granted ball valves are not good at regulating water flow so may have to change them out. We have great water pressure, 40 psi, from the well at the cattle tanks. Seems when you try and regulate the water temp you end up shutting down flow through the heater and then have to shut everything off and turn it back on to get hot water again, then it gets to hot start adding cold. Can't get maintain a constant comfortable temp. Was thinking about getting a real shower mixing valve or changing to a gate valve instead of the ball valves.
Thoughts, suggestions, ideas or how do you guys regulate yours?
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creeky
Member
# Posted: 22 May 2018 08:40
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I just use one tap. I set the temp at the water heater manually. Its not great. But it works.

FYI. My cold water line froze couple years back and now the valve doesn't work. So its hot only for me.

FishHog
Member
# Posted: 22 May 2018 11:23
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I do most of my adjustment at the Eccotemp as well. Really only need to do that once per trip depending on the incoming water temp. I set is a little hot for me as Mrs Fishie likes hotter showers than I do. Then I turn on a small amount of cold at my shower taps. But if you do too much I have the same problem with losing too much flow and the heater shuts off. It run off of water flow, not pressure, so if it drops it turns off and you need to restart.

Im not sure a mixing valve will help that, and they are very hard to winterize if you need to worry about that. A higher flow pump and possibly larger water lines might be needed if you want to keep using your setup.

Fanman
Member
# Posted: 22 May 2018 12:57
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I have a Bosch tankless heater in my cabin. The temperature setting (globe valves) in our shower is pretty touchy, too. Standard procedure is to turn on the hot water all the way, then once the hot water makes it to the shower and stabilizes, barely crack the cold, never touching the hot again.

You don't want to try to adjust the hot water flow, because if you reduce the flow to make it cooler, it initially comes out colder because there's less hot water mixed with the cold, but it also reduces the flow through the heater, meaning the water spends more time in the heater coils and thus gets hotter, cancelling out any change. So you keep reducing the hot flow until as you found out, it shuts off.

Popeye
Member
# Posted: 22 May 2018 13:04 - Edited by: Popeye
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I have the same issue as the OP and follow the same procedure as creeky. A solution I though of is to drive a second well. I would then have a well for hot water and a well for cold water. Of course this would mean having a second pump. It is a quick and inexpensive solution, but I have not found the need for it yet.

paulz
Member
# Posted: 22 May 2018 14:56
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I have an L5 with standard valves in the shower. Haven't achieved an even shower temp yet using the cold valve to adjust.

Fanman
Member
# Posted: 22 May 2018 15:28
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Fluctuating water pressure as the pump comes on and off will also affect the temperature.

rayyy
Member
# Posted: 22 May 2018 16:50
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Creky's right,just one line feeding the water heater and you ajust the flame up or down on the heater to find your comfort level.

sparky30_06
Member
# Posted: 23 May 2018 06:56
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thanks guys, it's not a water supply issue from the well. I'm not running the system off a small pump it's from a submersible pump to a holding tank that feeds all the water tanks at the cattle pens. I have enough water pressure and flow to remove paint in the shower! lol

I'll play with the temp on the unit and see how that works.

Do you see yourselves adjusting the setting as the incoming water temp changes from summer to winter?

sparky30_06
Member
# Posted: 23 May 2018 07:00
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OH and not to worried about winterizing. Don't have to worry about freezing in south Texas much but I have an idea on how to drain it down. Most shower mixing valves have a port on the bottom that goes to the tub, i can place a ball valve that to act as a drain. All my lines are over head, sloped, and have two low point drains, if needed. That's what happens when a Yankee moves to the south, he thinks about frozen water lines

FishHog
Member
# Posted: 23 May 2018 08:11
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Quoting: sparky30_06
Do you see yourselves adjusting the setting as the incoming water temp changes from summer to winter?


absolutely, I have a holding tank, so it stays pretty constant for a week while I'm there, but have to do an initial adjustment at the beginning of most trips.

Again, its not a water pressure issue, its a water volume (flow) issue that shuts your unit down. A completely separate cold water supply would fix your problem as well. But when you turn on your cold, it reduces the volume of water going into the water heater, thus shutting it off.

silverwaterlady
Member
# Posted: 23 May 2018 10:56 - Edited by: silverwaterlady
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We just use one line as well and adjust the temperature via the tank.

If we just pumped water out of the lake it hasn't been in our holding tank on our water tower where we get full sun most of the day.

So we do need to adjust the dial on the on demand shower to edge closer to the winter side.

sparky30_06
Member
# Posted: 23 May 2018 15:37
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guess i should have got an indoor unit and found a place to to hang in inside or maybe i'll switch to a tank heater.

sparky30_06
Member
# Posted: 24 May 2018 10:56
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ok so my mind has been working OT, how can I keep from the cold water flow shutting down the hot water flow. Maybe an orifice on the cold water line restricting the flow. maybe some check valves or what about a recirculating pump and a check valve to keep the hot water line constantly flowing? The water heater should throttle down and eventually shut off if the water temp reaches the set point.

Thoughts?

Seeing that I will have multiple different people using this and they will all want a different temp. If it was just me, I'd be good already

FishHog
Member
# Posted: 24 May 2018 12:50
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1)a larger pump giving you more flow should work. Or a completely separate pump and water line for the cold water, so that turning that on doesn't affect the hot at all.

2)Possibly a small pressure/accumulator tank on your hot water line before the heater, but still might be affected when you turn on the cold.
like this https://www.amazon.ca/Shurflo-182-200-Accumulator-Tank/dp/B000N9VF6Q?th=1&psc=1&sourc e=googleshopping&locale=en-CA&tag=smacab-20&ref=pd_sl_14bj0z5arx_e


3) a small orifice in your cold line, or a very fine on/off valve so you don't turn on too much and affect your flow.

ICC
Member
# Posted: 24 May 2018 13:31
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I would install a single handle mixer

FishHog
Member
# Posted: 24 May 2018 16:47
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That won’t work. Same problem your flow in your water heater will drop and it will shutdown

ICC
Member
# Posted: 24 May 2018 20:26
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If that is the case it sounds like a poor choice for a water heater to me.

ICC
Member
# Posted: 24 May 2018 20:27
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What is the rated flow rate for the shower head? Perhaps a lower flow head would help.

sparky30_06
Member
# Posted: 25 May 2018 07:20
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Quoting: ICC
If that is the case it sounds like a poor choice for a water heater to me.


You are probably correct with that statement but yet I have seen instant hot water heaters used in homes and other cabins, that I have stayed in, that use conventional sink and shower controls and normal shower heads.

Trying to figure out how they do it.

I'm heading back out tonight and will mess with it more over the long weekend and 100 degree temps.

FishHog
Member
# Posted: 25 May 2018 08:28
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Quoting: sparky30_06
Trying to figure out how they do it.


more than likely they have a larger unit than the L10. Its a great unit at a great price, but it has its limitations. Flow rate being one of them.

You can look it up, but the required flow rate is around 2gpm if my memory is right. Most people buy the package that includes a pump that puts out 2.3gpm. That doesn't give you much room to split flow. That is most likely your problem. A higher flow rate pump would solve that, its not the heater. Its doing its job.

Check out the specs on the L10 and your pump and I think you will figure it out pretty quickly.

sparky30_06
Member
# Posted: 25 May 2018 09:12
Reply 


FishHog i think you are correct on figuring out the root of the problem just need to figure out how to correct it and a different heater may be the solution. I'll just use this one to feed my power washer.

I have a flow rate higher than a small 12 volt pump. The water system is the same as you would have in a house. 220 Volt submersible well pump feeding into a 40 gallon pressure tank in the well house. The shack is fed by a 3/4" line and even after i drop down to 1/2" lines we still have over 10 gpm.
So flow to the shack isn't the issue

It seems that the cold water volume is overtaking the hot when we try to mix them causing the hot water flow to drop below the required rate. So need to drop the output temp of the unit low enough that we are only mixing a small amount of cold water in so that we can maintain high enough flow to keep the unit lit.

May need to find a fancier unit with a modulating flame so we can use a lower flow rate. I bet that's how the places i have stayed in have done it. Not a bigger unit but a fancier one. Time to do some more research.

ICC
Member
# Posted: 25 May 2018 10:10
Reply 


Better heater is needed, as was mentioned.

You need to know the lowest temperature of the incoming cold water plus how much the water must be heated and what the rate of flow through the heater is. All heaters should have a table that can be used to see if the heater will heat the water enough at the desired flow rate. Also look for the lowest flow rate that will turn on the burner and keep it on. Then make certain the pump can supply the total volume.

I don't use an on demand heater as I heat via solar with a stoarage tank, but a buddy has a Rinnai on demand in his home. Another has a Bosch. There places seem to have hot water that works fine. They cost a lot more than these low cost units.

sparky30_06
Member
# Posted: 29 May 2018 07:15
Reply 


So as i was driving out to the lease, 4 1/2 hours of time to think, I had another thought. Shower heads these day have restriction in them. So when i got camp opened up i took the shower head off and started to pick and dig at the restriction plate. Got it dug out. Adjusted the heater to the lowest burner setting and turned the water flow to max on the unit. Tried it with just hot water only and it was still to hot for me so opened the cold water valve in the shower slowly and amazing i was able to adjust the temp now. Granted the ball valves are extremely touchy, granted ball valves are not designed to regulate later i will change them out with a better style, maybe a good needle valve.

But long story short it works & lots of lessons learned.

FishHog
Member
# Posted: 29 May 2018 07:35
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Good stuff. Glad it worked out.

paulz
Member
# Posted: 14 Jul 2018 20:58
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Well i just had a shower and again same problem as sparky, turn on the cold and it shuts off the L5. Hmm, I have pretty good water feed under just gravity (not enough to fire the L5 though), if I plumb the cold water valve direct to gravity, it won't shut off the L5, no?

Or, I could cut a door in the shower wall to reach the knob on the L5...

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