Hobby_Man22
Well-known member
Not sure if its the valve cartridge all gunked up or the small on the demand water heater. I had a shower valve not put out hot water once, but never restricted flow
Will a small on demand water heater restrict water flow?
- Thread starter Hobby_Man22
- Start date
finn
Well-known member
I think most modern shower valves have a pressure balance feature. I recall having almost no flow at all when I had the water heater shut off at the tank.. Flow returned to normal when I opened the valve at the tank.
That was with a Kohler shower faucet.
That was with a Kohler shower faucet.
OP
Hobby_Man22
Well-known member
No flow on the cold side either? Mine makes plenty of cold water. Its when you turn it to hot that it turns to barely anything coming out
finn
Well-known member
Correct. No or at best, meager flow on the cold side.
Threw me for a loop for a second or two. What happened is we shut down our Marana house for the summer. I shut the hot water tank at the tank rather than shutting the main supply off. We had people occasionally run water to keep the traps full over the summer….shower wouldn’t flow.
When we returned in the fall, sure enough no water from the shower head. Turned the valve at the tank back on, and both hot and cold ran through the shower valve. It’s a pressure balanced valve, so nothing flows if there isn’t pressure at both hot and cold sides.
I recall having the same situation on a rehab we did on another house bjust before COVID with another brand of faucet, perhaps Delta.
I figured out that the main shutoff for the entire house in Az is easier to reach than the valve at the tank, so our friends bring their own water in gallon jugs now to fill the traps and toilet bowls when we’re gone over the summer. I’m a little gun shy about leaving the water system pressurized, as one of the neighbors had a toilet fill hose break a couple of years ago when he was out of the country, flooding the entire house.
CraigStu
Well-known member
I agree w/ your idea of shutting off the entire house water. We used to be friends w/ a realtor. She told us of another realtor selling a house in the fall that the people had moved out of. It got cold, some hose popped on the second floor, it got warm and same deal. $100 to fix the popped hose and many $1000s to fix all the water damage.
OP
Hobby_Man22
Well-known member
Well, it's only the shower that does it. The kitchen sink doesn't have the same issue
finn
Well-known member
Mine was the same. Sinks worked when flow to the water heater was shut off, but the shower didn’t.
Shower was the only thing with a pressure balance valve.
That would have been good information to lead with...
OP
Hobby_Man22
Well-known member
We're not all perfect
Stuart in MN
Well-known member
Tankless heaters typically require some regular maintenance to prevent them clogging up with minerals and scale. Has that been done recently?
duneslider
Well-known member
I have had this issue with cartridges in shower valves, can't remember what brand they were in the house I lived in then. Swapped the cartridge and all was good. I do know whatever brand it was it was common and the local home depot had it in stock.
OP
Hobby_Man22
Well-known member
We have horrible well water here. Lots of iron, lots of calcium etc.
CraigStu
Well-known member
Now that you mention that, me too. Our last house was 20 yrs old when we moved in. We lived there for 5 years and I remember replacing the shower cartridge twice. It was either Moen or Delta and HD had the cartridges on hand.
OP
Hobby_Man22
Well-known member
So I cranked the tankless hot water heater up to 140 (high as it goes) definitely don't want to be under it at that temp. Let it run for a bit on full hot. Anyways, next time i took a shower I didn't notice much of a flow drop between hot and cold. That hot water run must have cleaned out that valve or something. I bet if you removed the valve and dropped it in a pot of boiling water it would come back out sparkling clean assuming the orings were still good beforehand