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RESOLVED: Can a limit be set water heater before it turns on?

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  • Sep 7th, 2021 2:20 pm
[OP]
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Feb 4, 2010
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RESOLVED: Can a limit be set water heater before it turns on?

I have a 189L John Wood water heater on natural gas, which is probably too big of a unit for the house but it's owned (not a rental). Is there a way to set a limit on the threshold water heater before it turns on? It seems like anytime the water is turned for a short time the water heater starts refilling. I'm not sure how much money and energy this is wasting but would like to see if there's anything I can about it.

Question has been answered - thank you
Last edited by hierophant on Sep 6th, 2021 8:08 pm, edited 1 time in total.
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Sep 27, 2006
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Not so easy there Ma…
You can reduce heat loss by turning down the tank temperature.
[OP]
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fergy wrote: You can reduce heat loss by turning down the tank temperature.
I'm asking if threshold for the QUANTITY of water used can be changed before it starts refilling - I'm not sure how the temperature plays into that.
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Nov 17, 2012
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hierophant wrote: I'm asking if threshold for the QUANTITY of water used can be changed before it starts refilling - I'm not sure how the temperature plays into that.
The water heater doesn't empty/fill up. It's always full and is pressurized along with the rest of your hot and cold water supplies.

The only way for hot water to come out of the tank is for cold water to go into the tank. Plain and simple.

Don't over think it - they're efficient and well insulated. Just enjoy your hot showers and focus energy saving money elsewhere.
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Not so easy there Ma…
hierophant wrote: I'm asking if threshold for the QUANTITY of water used can be changed before it starts refilling - I'm not sure how the temperature plays into that.
There's no threshold devices per se to do that. You could reduce the overall water pressure, I limit the pressure myself as I find the shower heads at my place seem to waste a fair bit of water otherwise.
[OP]
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torontotim wrote: The water heater doesn't empty/fill up. It's always full and is pressurized along with the rest of your hot and cold water supplies.

The only way for hot water to come out of the tank is for cold water to go into the tank. Plain and simple.

Don't over think it - they're efficient and well insulated. Just enjoy your hot showers and focus energy saving money elsewhere.
OK...I was seeing if there was anything I could do to offset having a water heater twice the size than necessary but I guess not.

@fergy reducing the water temperature I guess could have a nominal impact for keeping the water heated at a lower temp
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Feb 11, 2007
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hierophant wrote: OK...I was seeing if there was anything I could do to offset having a water heater twice the size than necessary but I guess not.

@fergy reducing the water temperature I guess could have a nominal impact for keeping the water heated at a lower temp
2x the size doesn't mean you lose 2x the heat. The surface area will be minimally larger, and heat loss won't be significantly more. Turn down the temp if you want to save a buck or 2 a month.
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Jun 14, 2008
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Why would you want to do that? You are still heating the same amount of cold water that replaces the hot water you use, and the tank has a exact same amount of surface area to lose heat no matter how much water is in it.

It will literally does nothing to save energy or money.
[OP]
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The question has been answered. No need to repeat what's already been said. Slightly Smiling Face
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What’s really important with a tank heater is to make sure it’s maintained.

On our old one, we noticed the water wasn’t as hot as it had been.

The cold water enters the tank from the top but the pipe goes down to the bottom of the tank. So cold water goes in at the bottom.

The hot water pipe in the tank is shorter, so the water at the top of the tank is “pushed” into this pipe as cold water enters at the bottom.

Our cold water pipe had corroded and broke off, so cold water was dumping into the top of the tank and mixing with the hot water that was being pushed out and delivered to the shower etc.

There is a sacrificial anode rod in the tank (I believe they all have these) that works to prevent this but it has a lifespan and needs to be replaced.

You could switch to tankless but you’re not going to save a ton of money, they’re expensive and more complicated than a tank heater.

Like I said before, there is much lower hanging fruit for efficiency savings than a maintained reasonably efficient hot water tank.
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Can't even imagine how big that is and what a 189L hot water tank looks like. How old is it?

Might be interesting to post the porn pic. Lol.
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This is the regular size that almost every house hold has in GTA.
Popularly known as 50 gallon
gr8dlr wrote: Can't even imagine how big that is and what a 189L hot water tank looks like. How old is it?

Might be interesting to post the porn pic. Lol.
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For the longest time, 40 US gallon (152 L) hot water tanks were the norm with 50 gallon (189 L) being considered an "upgrade" (or at least it was considered an upgrade when my house was built in 1992). Now with homes having multiple bathrooms with multiple tubs/showers, 50 gallons is pretty much standard.
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newlyborn wrote: This is the regular size that almost every house hold has in GTA.
Popularly known as 50 gallon
LOL. For some reason I was translating litres into gallons when I read it. Nevermind...that's just avg sized then. Not sure why OP thinks they need to do anything.
We're all bozos on the bus until we find a way to express ourselves...

Failure is always an option...just not the preferred one!
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Jan 25, 2007
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Paris
Might want to look into a water heater wrap insulation blanket if you need more?
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Dec 21, 2020
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What you actually want is a thermostatic mixing valve on the water heater and to turn the temp on it UP. The thermostatic mixing valve will mix the hot water with cold water to get to the temp you want. It sounds counter intuitive but basically you need LESS hot water to flow out of the heater (as some of the flow will be from the cold water mixed in). This causes the tank to require to heat LESS water back to the temp you set it on. Setting the tank higher is actually not much more energy to hold that heat. Especially since you are only heating a smaller amount of the fresh cold replacement water.

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