discussion Rants etc.....

[sswilson]

140f = 5 seconds to scald
130f = 30 seconds to scald
120f = 120 seconds to scald

I use these on electric tanks. You'd have to protect the hose from the vent for gas if it wasn't a two pipe or direct vent HE setup.
CASH ACME 24832

So..... is that a mechanical thermostat valve on the hot water output (from the tank) which opens regulates a cold water input for a constant max tank output temp?

If it is.... isn't that essentially doubling up temp regulation since you can already set a default max temp on the HW tank itself?

I'm struggling to understand the reasoning behind this in a residential settings since we should already be setting a max temp on the tank.

edit: I can see the application in a commercial setting where you might want to have a relatively high temp on your supply line for applications which require high temps, but then also want the ability to dial that supply line down for things like bathroom sinks so that your employees (or customers) can't scald themselves if they don't mix in some cold first.

 

[SugarJ]

Can't sanitize at 120f, but most dishwashers have a high temp option. I use a thermostatic mixing valve because kids. It's a very dumbed down version of an eye wash stations and can't go higher than 120f.

Modern dishwashers have a heating element that heats the water to 150F plus in the machine to sanitize. When they first became popular in the 70's they didn't have the heating element and tank temps were recommended to be around 150F if you had one.

I'll have to look into the thermostatic mixing valves. If I'd known about them I would have put one in while my kids were little. Thanks.

 

[JD]

I'm struggling to understand the reasoning behind this in a residential settings since we should already be setting a max temp on the tank.

I think the issue is your tank has to be >140F to kill legionnaires disease? But that's too hot at the tap. So it lets you keep the tank hot, but all the output is only 120F.

 

[clshades]

I think the issue is your tank has to be >140F to kill legionnaires disease? But that's too hot at the tap. So it lets you keep the tank hot, but all the output is only 120F.

Legionella can be killed at 120f it just takes longer. 140f is recommended as it takes seconds instead of hours. It's also recommended to run your hot water through all the fixtures @140 if you've taken a trip away from home for a week or more.

The whole "I must have brought something back from my trip" is actually your own home.

This is one of the reasons hospitals recirc the hot water directly to the fixtures. Nightmare install but it works.

 

[clshades]

So..... is that a mechanical thermostat valve on the hot water output (from the tank) which opens regulates a cold water input for a constant max tank output temp?

If it is.... isn't that essentially doubling up temp regulation since you can already set a default max temp on the HW tank itself?

I'm struggling to understand the reasoning behind this in a residential settings since we should already be setting a max temp on the tank.

edit: I can see the application in a commercial setting where you might want to have a relatively high temp on your supply line for applications which require high temps, but then also want the ability to dial that supply line down for things like bathroom sinks so that your employees (or customers) can't scald themselves if they don't mix in some cold first.

There's two types of mixing
Point of source
Point of use

Point of source is easier and cheaper or you end up with a mess of crap under every sink. One point of source costs about the same as 2x point of use. If you factor in the labour it's about the the same money. A tank kit on PEX takes me 30 minutes. Copper takes an hour.

I run my tank at 150f and the mixing valve brings it back down to 120f. I basically turn a 40 Imperial gal tank into a 55(ish). Wife can have a full bath and I can still have a decent shower.

Since tanks are only good for 10-12 years I just take whatever I can get out of it in that time frame. In BC, tanks older than 12 years, can potentially void the insurance.

If you have an atmospheric tank I would definitely put some metal between the flex hose and the exhaust venting system.

 

[clshades]

Point of use without the fittings and flex connects.

 

[gingerbee]

my tank temp is at 140+ on the second lowest setting, I am thinking about maybe adding some point-of-use mixing valves in the future. I will see how this goes, so far so good.

My understanding SSwilson it is for the reason JD mentions above and to prevent people/kids from getting burned.

 

[Marzipan]

Where did you hear that?

this is what we were told...turn the water tank temp up a bit to help make the dishwasher more efficient / effective. it's also recommended from appliance stores that put up dishwasher reviews on YouTube.

 

[gingerbee]

The only thing I am a little worried about is the new Moen kitchen faucet I have uses flex line so hoping the temp at 140+ is not a problem, just thought of this today when I was under my kitchen sink.

 

[clshades]

The only thing I am a little worried about is the new Moen kitchen faucet I have uses flex line so hoping the temp at 140+ is not a problem, just thought of this today when I was under my kitchen sink.

Not an issue. 140f is the recommended temp to a kitchen sink anyway. Most people have dishwashers which is how everyone should be doing dishes for sanitation reasons.