# Tankless Water Heaters



## BumbleBee (Jan 24, 2015)

So guys, this is what I have. I have to figure out why this homeowner's two side by side tankless water heaters aren't acting right. They were installed by some hack handiman and now I'm just confused. They weren't installed in line, but both hots were tied together underneath the house. Now it takes absolutely forever for the lavatories to get hot, but the shower doesn't take too long. The kitchen sink takes forever to get hot too. 

I sent my guys over there and told them to cut out any slack in the pex feeding the bathrooms and to completely separate the two water heaters. One water heater would provide hot water to one side of the house and the other would provide hot water for the other side of the house. They said they did that and it didn't really solve anything, but now the kitchen sink and the laundry sink has some weird stop and go flow. They did discover that neither thermostat had been installed... Could that be the entire problem? Each tankless has 3/4" gas line feeds which come off a 1" gas man. I'm going over there now and checking out everything. Unfortunately I'm not really a tankless expert... Anyone have any clue what maybe going on? I would really appreciate any help. Thanks!


----------



## MACPLUMB777 (Jun 18, 2008)

Start with doing a gas calculation you may be overdrawing the supply !
also check out the venting,
Basic do a install plan as if you are starting without the heaters in place and see how many mistakes were made correct them and then solving the other problems
as a master service agent for all the wtr/htr mfg's in my opinion most problems start with a bad install !


----------



## titaniumplumbr (Jun 11, 2014)

It's a lot like a review system which isn't installed correctly as 50/50 ( even though both are on a constant recirc whichever half has less offsets and footage will heat first


----------



## Bouk (Jan 4, 2009)

Just as Jerrymac stated,Perform gas calculation(total BTU count/distance...)Also rule out that your faucet aerators are clear of trash if aerators are clogged tankless will not initiate if minimum flow is not detected.If it is a navien or noritz go into maintenance monitor(you will need a remote controller)and see what flow rate is while faucet is running if flow rate is below minimum flow rate for unit clean aerator and recheck you will know if you don't have remote if minimum flow is met if unit starts when faucet is opened.Don't be trick because sometimes the unit(s) will initially start up and after a short time will shut off because minimum flow not maintained.If unit is installed incorrectly recommend HO make all corrections,replace units(if there is lots of damage to unit) or move on.Some homeowner can't understand why it is so expensive correct someone else problem that should have been done in the first place.Remember once you touch it you own it.


----------



## yaacov (Aug 8, 2012)

Not only is a low flow rate an issue but depending on the model a high flow rate can be an issue as well. If too Mich water is being pulled the unit cannot heat the water. Just don't open the shower handle all the way or close the angle valves slightly. Discovered this when we did a bathroom reno. The rest of the home (steel piping) got hot water but the new bathroom (pex) didn't.


----------

