Under sink water heater

[Chattrat]

I installed a 2.5 gallon 120volt water heater under my kitchen sink to give me quicker warm/hot water until the water from the main water reaches the kit faucet (approx 40 feet). I am using it "in line" with main water heater. All the original plumbing piping (including the feed to the kitchen sink) runs in the slab from garage to user locations. All my connections to hook up the 2.5 tank under the sink is regular flexible sink and visible for inspection for leaks.

The input of the 2.5 tank (blue) which normally would be feeding cold water is now fed gradually cold to warm to hot water from my main water heater. It runs through the inline pressure relief valve. I will set the temp for this 2.5 tank at a warm setting not real hot. As stated in another past discussion regarding the same type of installation, I am expecting the thermostat in the 2.5 gallon tank to cut off once the hotter temp water from the (garage located) main water heater reaches a higher temp. Will the inline pressure gauge with a red release handle function OK with this setup?

I plan on using a Wi Fi plug receptacle module on a timer to limit the heating to expected usage times. Any feedback for possible problems appreciated.

 

[MicEd69]

It runs through the inline pressure relief valve. I will set the temp for this 2.5 tank at a warm setting not real hot. As stated in another past discussion regarding the same type of installation, I am expecting the thermostat in the 2.5 gallon tank to cut off once the hotter temp water from the (garage located) main water heater reaches a higher temp. Will the inline pressure gauge with a red release handle function OK with this setup?

What do you mean by an "inline pressure relief valve"? Are you talking about the T&P valve on the water heater tank?

What is an "inline pressure gauge with a red release handle"?

 

[breplum]

OP, a tank water heater will always need a pressure relief valve piped to the outdoors.

 

[Chattrat]

What do you mean by an "inline pressure relief valve"? Are you talking about the T&P valve on the water heater tank?

What is an "inline pressure gauge with a red release handle"?

I mispoke it is a T&P valve it screws on to the input nipple (blue) on the top of the unit as per instructions from the water heater manufacturer info with tank. It has a red handle that you pull to release ?pressure?. Sorry about the confusion I am not a plumber and some of my terminology may not be correct.

OP, a tank water heater will always need a pressure relief valve piped to the outdoors.

this unit has a short flexible (2ft) plastic drain tubing for the T&P valve.

 

[MicEd69]

You need to show a picture of your water heater. There should be three connections to the tank. One is for the cold water inlet, one is for the hot water outlet, and one if for the T&P valve. You mention that the T&P valve is to be screwed to the inlet nipple (blue). I think you are mistaken or are reading the instructions incorrectly. Again, a picture would be most helpful.

Your description about connecting the hot water line from your main water heater to the cold water inlet of the 2.5-gallon water heater, and the outlet of your 2.5-gallon water heater going to the hot water faucet connection is correct. As is setting the temperature of your 2.5-gallon water heater lower than your main water heater. The hot water from your main water heater will satisfy the thermostat of the 2.5-gallon water heater and it will not fire as long as hot water is being used.

Depending on the code where you live and the location of your water heater, the discharge line from the T&P valve needs to be routed to the outside or at least to a safe place should the T&P valve open. It cannot be reduced in size either.

 

[Chattrat]

You need to show a picture of your water heater. There should be three connections to the tank. One is for the cold water inlet, one is for the hot water outlet, and one if for the T&P valve. You mention that the T&P valve is to be screwed to the inlet nipple (blue). I think you are mistaken or are reading the instructions incorrectly. Again, a picture would be most helpful.

Your description about connecting the hot water line from your main water heater to the cold water inlet of the 2.5-gallon water heater, and the outlet of your 2.5-gallon water heater going to the hot water faucet connection is correct. As is setting the temperature of your 2.5-gallon water heater lower than your main water heater. The hot water from your main water heater will satisfy the thermostat of the 2.5-gallon water heater and it will not fire as long as hot water is being used.

Depending on the code where you live and the location of your water heater, the discharge line from the T&P valve needs to be routed to the outside or at least to a safe place should the T&P valve open. It cannot be reduced in size either.

This picture is before I removed the in line fitting with the red handle on the left side (red side nipple output) . There are no other connections to the tank. Based on a comment I was told to instead put the T&P valve on the input (blue side) nipple. This installation is under island sink. House is on slab. All pipe is in slab to user locations. If needed I can get creative and add a larger drain container. I am holding off on re installing the T & P valve based on feedback just for a short time.

Thanks for helping.

 

[MicEd69]

If I was going cheap, I think I would have paid another $16 and got the next better model. I'm not sure how well the "in-line" T&P valves work. Good luck.

 

[Twowaxhack]

This picture is before I removed the in line fitting with the red handle on the left side (red side nipple output) . There are no other connections to the tank. Based on a comment I was told to instead put the T&P valve on the input (blue side) nipple. This installation is under island sink. House is on slab. All pipe is in slab to user locations. If needed I can get creative and add a larger drain container. I am holding off on re installing the T & P valve based on feedback just for a short time.

Thanks for helping.

View attachment 47857

You need to put that safety valve on the cold side according to the directions.

 

[breplum]

FYI the plumbing codes are designed for public safety.
That little PRV device is no -doubt not a tested/code-approved pressure relief device.
When this little unit fails, you could consider a Grundfos bridge mixer at the sink and pump at your water heater or the many brands like Laing that have the pump under the sink.

 

[Chattrat]

I received a follow up with the manufacturer. My set up is Good. The pressure relief valve is set for 108 from the factory. They are confident in the performance of the tank and this pressure relief valve.

I am also going to use a Wi Fi receptacle module to plug into to set typical user times. That way I'm not heating water with this unit 24 a days, saving power cost and hopefully extending the life of this small water hearer.

So I'm all set. Thanks all for trying help.

 

[havasu]

Just curious, but is that unit UL approved?

 

[MicEd69]

Just curious, but is that unit UL approved?

I was curious as well, and I found a U-Tube video about this unit. Here is a screen shot of the side of the unit. It shows no UL listing sticker. Also, note the "Rated frequency" of 50Hz.



The design frequencies are often listed as 50Hz/60Hz for universal items. That may not be a huge problem with this unit, but that coupled with the missing UL listing would leave me very uneasy. I think I would have spent another $100 and purchased a similar BOSCH unit. It's made in the USA, UL listed and has the standard P&T valve.

Chattrat, I'm not trying to scare you or be mean here, but you may want to rethink your installation. You said you have received communications from the manufacturer. Maybe at least contact the manufacturer again and if the nameplate on your unit does show only 50 Hz, ask them to provide written verification that you installing this on a 60Hz supply is acceptable and still covered by all warranties. That won't mean ANYTHING at all should something go wrong, and will not help in any lawsuit, but might make you feel better.

 

[RS]

I think that will work fine, but I think the T&P valve shoud be on the output side of the heater, that's where it's the hottest. I installed a simmilar heater in our primrary home, in the crawl space under the master bath. It works great, the main water heater is a long way away, this way I get hot water in the shower quickly and it doesn't change temperature while showering. I leave it energized any time we are home, when we are gone for any amount of time (overnight) we shut off the well pump and both water heaters. I don't think a water heater cares if it's 50 or 60HZ it's just a heating element. Also, if it's working properly the T&P valve shouldn't discharge anything, but maybe you should have a bigger container for that. I didn't see where you mentioned if you're on a well or municipal water, if it's municipal water you should have an expansion tank by your primary water heater.

 

[MicEd69]

I think that will work fine, but I think the T&P valve shoud be on the output side of the heater, that's where it's the hottest. I installed a simmilar heater in our primrary home, in the crawl space under the master bath. It works great, the main water heater is a long way away, this way I get hot water in the shower quickly and it doesn't change temperature while showering. I leave it energized any time we are home, when we are gone for any amount of time (overnight) we shut off the well pump and both water heaters. I don't think a water heater cares if it's 50 or 60HZ it's just a heating element. Also, if it's working properly the T&P valve shouldn't discharge anything, but maybe you should have a bigger container for that. I didn't see where you mentioned if you're on a well or municipal water, if it's municipal water you should have an expansion tank by your primary water heater.

You are correct that electrical resistance heaters do not really care if they are 50 Hz or 60 Hz. However, my point is that this company in China designed this with whatever design parameters they use, and that it is not tested per safety standards we have in the United States.

 

[Twowaxhack]

I think that will work fine, but I think the T&P valve shoud be on the output side of the heater, that's where it's the hottest. I installed a simmilar heater in our primrary home, in the crawl space under the master bath. It works great, the main water heater is a long way away, this way I get hot water in the shower quickly and it doesn't change temperature while showering. I leave it energized any time we are home, when we are gone for any amount of time (overnight) we shut off the well pump and both water heaters. I don't think a water heater cares if it's 50 or 60HZ it's just a heating element. Also, if it's working properly the T&P valve shouldn't discharge anything, but maybe you should have a bigger container for that. I didn't see where you mentioned if you're on a well or municipal water, if it's municipal water you should have an expansion tank by your primary water heater.

You don’t want to put a relief valve in the hot side flow. Cold side is less corrosive but most codes require a t&p valve with the temp sensor innthe top few inches of the tank.

This DUMAFlotchee has one tyst screws onto the cold side per the instructions.

 

[RS]

You don’t want to put a relief valve in the hot side flow. Cold side is less corrosive but most codes require a t&p valve with the temp sensor innthe top few inches of the tank.

This DUMAFlotchee has one tyst screws onto the cold side per the instructions.

That's why I thought it should be on the hot side, on the cold side the temperature probe is sticking down into the dip tube, correct? But every water heater I have ever installed came with a T&P screwed into a dedicated port.
And your last sentence doesn't make any sense to me, or to Google!

 

[Twowaxhack]

That's why I thought it should be on the hot side, on the cold side the temperature probe is sticking down into the dip tube, correct? But every water heater I have ever installed came with a T&P screwed into a dedicated port.
And your last sentence doesn't make any sense to me, or to Google!

This T&P doesn’t have a temp probe I don’t think. It’s probably illegal to use here but I’m just lil ole me in Alabama , I’m not in charge

Some people agree with installing a T&P temp probes in the water flow, I personally do not. I personally will only install a T&P valve in a dedicated port within the top 6” of the heater. That’s the rule I live by.

 

[RS]

Yes, I probably would never buy a heater like that, it's too cheap to be any good! What I installed looked like a regular water heater, but only 2.5 gallons, with the hot and cold on top, and the T&P in the side close to the top. I expect it to fail anytime, I put it in 16 years ago, but we do have a water softener. For 5 months every winter it's blown out, as we are in Arizona. We heat the house to 50F, but just in case. The one I expect to fail any day is the one here in AZ, it 13 years old, terrible water and no softener!