New tankless installed and issues

[Jerry Tang]

newly installed A o smith tankless water heater I bought in year 2020 having issues. the water output temperature is not stable and the output showed 100 degree while we set it for 120, sometimes it jump to 138 degrees. Ao smith supper said it’s probably with a bad gas mix valve or bad installation. I am attached the pictures, is the installation done correctly? Also the venting is a concern, see the picture, can white pvc pipe go up from near the door up 4 feets from its current location?

 

[Jerry Tang]

Anyone please?

 

[Sponsor]

 

[GReynolds929]

How many btu's, gas type, ground water temp? The install looks ok, but you need a PVC pipe directing the condensate outside. You don't want it getting on metal as it will eat it up in no time. You should be able to redirect the exhaust as long as you are not near any openable windows or vented eaves

 

[Jerry Tang]

How many btu's, gas type, ground water temp? The install looks ok, but you need a PVC pipe directing the condensate outside. You don't want it getting on metal as it will eat it up in no time. You should be able to redirect the exhaust as long as you are not near any openable windows or vented eaves

It’s 180000 Btu and we have 1” pipe which good enough. Can you look at the outside picture where the vent terminated? It’s about 1 feet above the garage door, and it does not have a 90 drop. Is it ok?

 

[GReynolds929]

Like I said before you should be able to elbow up and elbow out, as long as you meet clearances. You can not just put an elbow on pointing down at the door.

What is the gas type? What is your areas groundwater temp? What is the gas pressure?

 

[Jeff H Young]

I dont see the venting as cause of temp being low , has a 1 inch gas line looks dedicated i dont see a mixing valve if there is a mixing valve then check temp on both sides of valve might need adjustement

 

[Jerry Tang]

Like I said before you should be able to elbow up and elbow out, as long as you meet clearances. You can not just put an elbow on pointing down at the door.

What is the gas type? What is your areas groundwater temp? What is the gas pressure?

It’s natural gas , ground water 50 to 55f, gas pressure 7wc. I already have 5 elbrows, if I extend the pipe up 5 feets I will need 3 more elbrows, looks like A O smith has a limit for max 5 elbrows??

 

[Jerry Tang]

I dont see the venting as cause of temp being low , has a 1 inch gas line looks dedicated i dont see a mixing valve if there is a mixing valve then check temp on both sides of valve might need adjustement

It’s the mix valve issue, we replaced it and seems better. My main concern is the venting if I can go up more about 4 feets up from the door, due to I have 5 elbrows already, and a o smith has limit of 5 elbrows ? And each elbrow add 5 feets to the max length?

 

[Jerry Tang]

It’s the mix valve issue, we replaced it and seems better. My main concern is the venting if I can go up more about 4 feets up from the door, due to I have 5 elbrows already, and a o smith has limit of 5 elbrows ? And each elbrow add 5 feets to the max length?

We replaced the gas manifold mix valve inside the unit

 

[Jeff H Young]

gas manifold mix valve ? i thought you meant a thermostatic mixing valve that some have on the water.
Also I thought you had a problem with function .
Ok well then the final issue is your vent well Youve got the manual I dont have it but install your vent to code and follow manual its in the manual if you are in a jam ask Ao smith tech team . you been running it 6 years have you been getting CO inside the house ? might be a window right above the vent too I dont know ?

 

[Jerry Tang]

gas manifold mix valve ? i thought you meant a thermostatic mixing valve that some have on the water.
Also I thought you had a problem with function .
Ok well then the final issue is your vent well Youve got the manual I dont have it but install your vent to code and follow manual its in the manual if you are in a jam ask Ao smith tech team . you been running it 6 years have you been getting CO inside the house ? might be a window right above the vent too I dont know ?

Can you check it for me? I have the picture here, any issues to have more than 5 elbows?

 

[Jeff H Young]

I dont know the specs on the vent system requirements

 

[GReynolds929]

Page 18 and 19 of the manual have the vent size and length requirements. Have the dip switches been set properly? Below 3000 ft you can have 5 elbows and max 45' of 3" vent pipe. Not sure how there's 5 elbows used on the exhaust vent run but if there is then you're stuck unless you can straighten the run out and eliminate an elbow or two.