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[ecc_33]

He has a 20 plate which is why I said he didnt need a mixing valve, the water doesnt stay in the plate long enough to reach a temperature that will scald

Sorry Scott, Not trying to go over your head just trying to give you a break lol!!!!! Scott has been so much help and i've been blowing him up over the last few weeks I figured I would post as to give him some break. Thanks Scott!!!! Making more since the more I learn about these things. ON EDIT: My wife is 8 weeks pregnant. Thats what im worried about and why I posted. We are not stupid so we know not to put a baby into something thats hot for us just wanted some feedback. thanks! Eric.

[Scott7m]

He has a 20 plate which is why I said he didnt need a mixing valve, the water doesnt stay in the plate long enough to reach a temperature that will scald

Sorry Scott, Not trying to go over your head just trying to give you a break lol!!!!! Scott has been so much help and i've been blowing him up over the last few weeks I figured I would post as to give him some break. Thanks Scott!!!! Making more since the more I learn about these things. ON EDIT: My wife is 8 weeks pregnant. Thats what im worried about and why I posted. We are not stupid so we know not to put a baby into something thats hot for us just wanted some feedback. thanks! Eric.

haha no problem at all

[automan77]

I have one installed. 

[martyinmi]

Mine's been in place since I built my first OWB. My son was only 3 or four at the time and we didn't want him getting accidentally scalded.
If I remember correctly, in Michigan, when you have an OWB professionally installed and your installer involves inspectors (mechanical and electrical), you need to have a tempering valve installed should you decide to heat your DHW. That's based on a conversation I had with John Paradine in the mechanical division at LARA in Lansing, Mi. a while back. I've never read it in their book, as they are very proud of it (nearly $90 shipped), so I'll take his word for it.
Of my friends, as well as friendly enemies who operate OWB's, I'd say that just over half of them use tempering valves.
If my water heater sits all day, it will be approximately 165-170 degrees on top and roughly 140 on the bottom. I run my boiler @ 190* on and 195* off.
I wrapped my side arm with a couple layers of insulation, and added another around my water heater.
I have my mixing valve set as high as it will go. I believe we are getting 123* at the tap, which I think is too hot, but my beautiful bride likes it that hot for laundry.
You all know the old sayin'- "If momma ain't happy.................... 

[Fourced]

He has a 20 plate which is why I said he didnt need a mixing valve, the water doesnt stay in the plate long enough to reach a temperature that will scald

I beg to differ, I have a 20 plate, water temp in the boiler is 160. Our tap will produce 140F water, I am using the water heater as a holding tank.

[cranman]

I prefer an aquistat in the top side relief hole of the tank set at 140 degrees F to run a pump up through the sidearm. I usually T off my return line to the boiler after going through the heat exchangers etc. and I T in the return from the sidearm a few inches down stream. Just doing another one right now actually. I have no experience with the new plate exchangers but think they may be superior to sidearms....Not as clumbsy to install anyways.

[cantoo]

I just installed 2 of them in my 2 houses. One is a stainless sidearm and the other is a 20 plate. Water from either one would easily burn you. I run my owb at around 155 or so. I've noticed that I don't have to turn the handle near as hot on my shower as I used to when it was electric heat and no mixer valve so I assume the water is hotter now. Willie is correct here in Ontario it is code.
And just a little FYI, most mixer valves sold here are Apollo, made in the USA so we're supporting you guys.

[slimjim]

Thanks Cantoo, with the way things are going we will need all the help we can get!

[CountryBoyJohn]

I got my cooking thermometer out tonight to test my hot water temps.  I did a test right off the bat, not knowing where I was in my burn cycle.  I got 129.  Then I took a shower and had some laundry going as well.  I checked again and got 136.  I didn't go out and see if the stove cycled. The sink I used was an average distance from the stove for my 3 water sources.  I have insulated plumbing lines in the house.  My stove is at 185.  I'm sure if I fired the stove, cycled through a bunch of hot water, I'm sure I could crack 140, but not much more than that. 

I did some looking around on "scalding" and it all depends on exposure time.  You can technically be scalded in 108 degree water, but it takes 10 hours of exposure.  140 degrees scalds in about 6 seconds.  130 in about 30 seconds.  It's a curve that depends on how long you are exposed to the water.  Scald being defined as a 3rd degree burn.

[ecc_33]

Alittle up date. Got stove running!!!!!! Water out of all sinks are HOT!!!!. Water out of the showers are fine. They have a built in mixing valve so I adjusted them. Pics to come of my setup and house. Trying to move in now.

[JDfarmer]

You absolutely really need a mixing valve. Especially if you have small children. Even if not, our water get up to 150-160F with the boiler. I installed mine in 45 minutes. You need a 120F one; mine is;
Aqua guard tempering valve;
3/4 model
Model number; "zw1017xlc"
by www.zurn.com
It was $129.00 I think. It works awesome. If the fire burns down, it just auto adjusts to the water heater temperatures.
If I restart the boiler it just auto adjust for the higher temperatures. Once you put it in, you don't need to mess with it. It won't let anything hotter than 120F out. It does NOT restrict the flow hardly at all. It's hardly noticeable. If it does for you, it's probably not installed correctly.
Sharkbite also makes one for 120F, but be careful they make one for 160F. You need 120F.
At 150F-160F you can get a third degree burn in 2 seconds!!!!! Not worth the risk. Get a valve, no questions.
A plumber will instal it for about $300 with the part included. For him; a 30min job
Good luck.
 

[Chas]

When I installed mine, I built a bypass around it. If I ever have any issues with it I can bypass it, remove and replace/repair it and not be without hot water while doing so. I will also bypass it in the off season just to hopefully prolong it's life. I also installed Ashcroft dial thermometers on the inlet and outlet to monitor the water temp in the tank and from the mixing valve. I works great and looks sweet!

[Wood Nutt]

Most all shower valves mix a volume of hot and cold water at your shower and does not monitor temps.  If your OWB increased in temp, you could see a raise in temp without changing the lever or knobs on your faucet.  I don't see how it could raise that fast, but really don't want to chance a scald so I installed the mixing valve.  Attached is a picture of the octopus I built.   The silver braided lines are what was added for the OWB and the copper are what was on the original hot water heater.

I have an electric demand heater (summer use) and a 30 plate exchanger hooked to the OWB for winter use.  I added an OWB bypass this fall and use a mixing valve on the OWB.  Last year I ran the OWB heated water thru the electric with it on, it is designed to be a supplemental heater too and would only come on when the water entering it was too cold.  This year I turned the breakers off to the electric one and its basically just serves as a pipe in the winter. 

My electric heater's control board adjusts the temp in the summer, so I don't run hot water from it thru the mixing valve.  My mixing valve is a Honeywell and they make two grades and one is for applications for uses such a showers where humans are at the end of the pipe.  That grade of mixing valve is more expensive, I presume for tighter quality control (and to pay the liability lawyers!).  The one I installed it the more expensive model.  With kids, the peace of mind of potentially not scalding them was worth the $100 bucks it cost.

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[JDfarmer]

When I installed mine, I built a bypass around it. If I ever have any issues with it I can bypass it, remove and replace/repair it and not be without hot water while doing so. I will also bypass it in the off season just to hopefully prolong it's life. I also installed Ashcroft dial thermometers on the inlet and outlet to monitor the water temp in the tank and from the mixing valve. I works great and looks sweet!

Yes, the bypass is a good idea for the summer when not using the OWB. I was going to do it but my plumber friend talked me out of it. He was worried that with it may reduce the water flow. Our water pressure is so good right now, I didn't want to mess with it. If I had Pex pipes not copper, I probably would have done a bypass. I just didn't have the time to do it, and if the flow reduces undo it with all the coper soldering.

[buckgrunt]

Mixing valves are a must when installing an in-floor radiant heating system.  My OWB temp is set at 188, but this is too hot for a radiant floor system as the floor would get too hot to walk on.  It is OK for regular baseboard heating.