Inlet Temp lift

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Holla

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I have a Westinghouse 199k btu residential tankless been installed 5 years without issues. (WGRTNG199) Over the last winter I had some cold showers as it was brutally cold and was told by Westinghouse support that the inlet temp was too cold and the unit was protecting itself from freezing. No error codes or anything on the unit. While that was part of the issue I then found the blending valve had started to leak so I replaced. That didn't fix the issue and finally support said I needed the matching new main board to go with it. OK, that solved the problem just as the extreme cold snap was lifting so who knows what the real fix was. Support also mentioned that this unit should not be installed for the extreme lift in central Wisconsin and suggested to install a small unit to pre-heat the inlet temp to keep it warm enough to allow main unit to work better. I was monitoring inlet temps as low as 38F at times during the cold snap and that is low enough to trigger the shutdown.

So, 1st question is any suggestions on a small electric tankless I can pipe inline to lift my inlet temp about 15 degrees to confirm the inlet temp to the main unit is always above 45F? I've looked at single faucet sink units but my concern is trying to plumb those with 3/4" pipe to keep my flow acceptable in the house.

2nd question, I'm getting some sporadic cold showers already and it isn't close to cold yet. Maintenance is up to date, no error codes but getting a cold shower at times multiple in a day. I then unplug and reset and then all is fine for a couple days. Anyone have similar experience?
 

WorthFlorida

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A large capacity tankless electric heater takes some serious power and they can be pricy. Here is a unit that has 3/4" fittings. What is nice about chronomite units is they will heat the water at very low flow rates. Only when the washing machine uses full flow of hot water when used or the tub spout is wide open to fill the tub. Dishwasher uses little water, a gallon or two per fill and it's a slow fill.

https://www.chronomite.com/product.aspx?ProductId=123

I do not know anything about this unit but here are just some of my thoughts.
Here is the manual and see page 9. I'm not sure if you unit has this feature. Doesn't make much sense that it will shut down for freeze protection. No heat and things can definitely freeze. The unit might be shutting down for time to heat the water to prevent freezing before turning itself back on?

https://www.manualslib.com/manual/862096/Westinghouse-Wgrtng199.html?page=9#manual

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Fitter30

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Can't find a wiring diagram for your heater. Anyone find one? Don't think heaters looking at water temp for freeze protection just ambient temp. Because of the ceramic heater.
 
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wwhitney

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wwhitney

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For a simple 2.5 gpm shower, if you want to temper water from 38F to say 45F, then you need 7 F * 2.5 gal/min * 8.34 lbs/gal *60 min/hr = 8800 BTUs/hr, or 2600 watts. So doable with a 240V/20A circuit, but you'd have to find a unit designed for large flows that you can set up for some a lowh heating power. E.g. the unit WorthFlorida cited is 240V/60A, or 3 times larger than required for minimal tempering. But a possible option.

How about installing a 20-40 gallon tank in front of the tankless, to passively temper the incoming cold water using the household space heating?

Cheers, Wayne
 

jadnashua

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I've measured my wintertime incoming cold water at 33-degrees! I had thought about a tankless system, but gave up on the idea for two reasons...first, the lack of adequate temperature rise, and second, without adding outside air, the space I had did not have enough volume for the burner size, and adding that had some legal issues due to home owner's association rules. By the time you add in the extra serial heating costs, you'd go a long ways towards paying for any standby losses, too!
 

Holla

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Thank you all for the input. I'm leaning toward a holding tank being the most cost effective way to go though I'd like to put a high flow low lift unit inline without spending another $1k to do it let alone the power requirements. I'll keep you posted.
 

Holla

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More info. I talked to support today and of course couldn't replicate the problem while I had them, but they did ask what my NG supply pressure is. No idea so I installed a gauge on the same line as the WH and I have less than .5PSI at the unit with no other appliances running at the time. How do I raise that pressure? At the meter I assume as I have no regulators inside. Can I do that or do I need to contact the utility? I also used a normal tire pressure gauge on the air inlet or the new gauge and got no reading at all. Pressing the pin to release pressure there is barely enough pressure to reset the Schrader valve. I'm going to close the NG valve above the gauge I installed and pressurize it slightly just to be sure the gauge is working. Only a couple pounds so as not to hurt anything. Stay tuned!
 

Holla

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OK, so much for that test. I checked the manual and the NG pressure range is 3.5" - 14" WC. Which is .50 PSI max so the gauge I installed doesn't even read in that small of increments. I need to connect a true WC gauge to check the real pressure. Back to the drawing board and the local hardware store.
 

Reach4

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OK, so much for that test. I checked the manual and the NG pressure range is 3.5" - 14" WC. Which is .50 PSI max so the gauge I installed doesn't even read in that small of increments. I need to connect a true WC gauge to check the real pressure. Back to the drawing board and the local hardware store.
I would watch that existing gauge when the WH is firing. If the pressure does not drop a lot, I would stop worrying about gas pressure. The main reason to continue with installing the more sensitive gauge would be that if the phone support person is looking for a reason to get out of the call, he won't have that as an excuse.
 

John Gayewski

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It's not gonna be your ng pressure. Tankless heaters are not for your situation. I'm sorry someone convinced you to spend so much money. Your could replace your water heater with a boiler and an indirect water heater and get all you need plus do some space heating.
 

jadnashua

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Was that pressure reading while the tankless was firing? If not, you may have a supply problem and be limiting your burner's output. What size gas supply pipe is it, and how far from the meter is it? A tankless system's burner (around 200KBTU) needs a substantial supply line. A much smaller one usually can support a typical water heater, but those usually only have a quarter to a third of the demand for gas.

I thought about a tankless system, but after investigation, decided it wasn't for me. It may not be for you, either.
 

hazimali

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How about installing a 20-40 gallon tank in front of the tankless, to passively temper the incoming cold water using the household space heating?
 
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