Hi,

A month or so ago I decided to remodel my bathroom. The bathroom is very small and a portion of it was taken up by the water heater tank. To get more space, I decided to install a tankless water heater. I demolished the bathroom, taking it down to the studs. A handyman friend of mine took over from there. He installed the tankless water heater, hanging it on the wall above the spot where the old water tank sat. He then installed new drywall and tiled the floor and shower. When I tried to run hot water through the tub spout, the tankless water heater shut down. It appeared that I needed larger pipes for gas. We had 1/2 inch pipes and the chart in the tankless water heater's manual (Bosch 2400) indicated a minimum of 3/4 inch gas pipes. I brought in a certified heating/cooling professional and he increased the size of the gas pipes to 3/4 inch. Now when I run water through the tub spout, the water heater no longer shuts down but the water does not get any hotter than about 80-90 degrees. Same with water through the shower head. I get hot water in the kitchen sink just fine. I had the gas utility company come out to increase the amount of gas pressure from the meter (3/4 inch gas pipe is maximum allowed by my meter). They basically doubled the gas pressure (from 6 to 12) but it did not change the situation. I still have only lukewarm water at the tub/shower. The tankless water heater diagnostics indicate that I have about 3 gallons per minute of flow at the tub spout, and a little more than 1 gallon per minute at the shower head. The kitchen sink flow is about 1.5 gallons per minute.

During the remodel I installed new Price Pfister fixtures in the shower. The hot/cold is a single-handle control (automatic balancing?) that you turn a small amount for cold, a larger amount for hot.

I am at wits end, and my co-workers would be really pleased if I were to take a shower!

All suggestions appreciated!

Terry

Try removing the mixing valve with eth main closed, put a towel over the valuve hole and have a friend turn the main back on, it that water the full temperature? If so I'd think your hot inlet in that valve is plugged up a bit. Inspect and clean the ports.

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Originally Posted by tbryant513

Hi,

A month or so ago I decided to remodel my bathroom. The bathroom is very small and a portion of it was taken up by the water heater tank. To get more space, I decided to install a tankless water heater. I demolished the bathroom, taking it down to the studs. A handyman friend of mine took over from there. He installed the tankless water heater, hanging it on the wall above the spot where the old water tank sat. He then installed new drywall and tiled the floor and shower. When I tried to run hot water through the tub spout, the tankless water heater shut down. It appeared that I needed larger pipes for gas. We had 1/2 inch pipes and the chart in the tankless water heater's manual (Bosch 2400) indicated a minimum of 3/4 inch gas pipes. I brought in a certified heating/cooling professional and he increased the size of the gas pipes to 3/4 inch. Now when I run water through the tub spout, the water heater no longer shuts down but the water does not get any hotter than about 80-90 degrees. Same with water through the shower head. I get hot water in the kitchen sink just fine. I had the gas utility company come out to increase the amount of gas pressure from the meter (3/4 inch gas pipe is maximum allowed by my meter). They basically doubled the gas pressure (from 6 to 12) but it did not change the situation. I still have only lukewarm water at the tub/shower. The tankless water heater diagnostics indicate that I have about 3 gallons per minute of flow at the tub spout, and a little more than 1 gallon per minute at the shower head. The kitchen sink flow is about 1.5 gallons per minute.

During the remodel I installed new Price Pfister fixtures in the shower. The hot/cold is a single-handle control (automatic balancing?) that you turn a small amount for cold, a larger amount for hot.

I am at wits end, and my co-workers would be really pleased if I were to take a shower!

All suggestions appreciated!

Terry

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Terry,

Were you able to find a fix for this? I have the same problem... I installed a Rheem RTG-53 tankless... I have all of the required pipe sizes (3/4" copper & gas)... I have a Kohler bath faucet that sounds like yours (hot/cold is a single-handle control)... I have a 1100 sq ft ranch home, with one bathroom...

I am lucky if I get up to 50 degrees in my tub/shower.... The odd thing is, I had good temperature when the 40 gallon tank water heater was in use just yesterday.

My problem seems to be a hot water pressure issue to the tub only... The sink in the bathroom has separate hot and cold handles... and when I turn on the hot, I get the same pressure that I did with the tank water heater...

But when I turn on the bath faucet, the cold water is overwhelming the Hot....

I took apart the bath faucet and inspected the impeller looking things (dont know what they are called) and they look ok and they turn freely... So, out of curiosity, I only installed the cold "impeller" and turned back on the main... without the Hot impeller to stop water flow, the hot water started flowing and the tankless heater kicked on & the water coming out was 120 degrees, but the pressure was fairly weak...

I shut off the main and put back in the Hot "impeller" and removed the cold "impeller" and turned back on the main & I would say that the amount of pressure was about 3-4 times stronger than the hot was.

So, would you guys say that I most likely have debris in the line? Or is it possible that the water heater is restricting flow? The water heater is capable of heating up to 5.3 gallons per minute, so I would think that the water heater isn't restricting flow...

If I do have blockage, what it the best way to try to clear it?

Help!

Barry
Milwaukee, WI

Barry and Terry,

Any solutions to this issue?? I think my tankless restricts the hot water flow too much as well..

No gunk, junk - just the heater itself...

Dano

Your Price Pfister tub/shower faucet has small plastic adjustment ring behind the handle that adjusts hot water temperature. It a safety device so old people or kids won't get scalded. It always comes factory pre-installed at luke warm setting. Remove the handle and remove the ring completely. You will have hot water. Takes one minute to do. Let me know how you did.

I actually think that my problem is two fold...

1) I think my low pressure from the water heater is because the water temp coming into the house is too low, so the water heater needs to try to heat it up to 110 degrees & that is where I lose some gallons per minute.

2) I have an old Nendecken (sp?) valve in my tub & I think I just need to replace it with a more modern fixture.. So, until I do my bathroom remodel, I just put a shut off on the cold water line under the tub in the basement & have the cold water shut off completely to the tub. I know that the water won't get any hotter than the 110 degrees I have the tankless set to.

Young1: read your detailed post. You have one of the two solutions to your problem:

1. You have debris inside your faucet.

2. You are not saying what type of faucet you have. But, if it is pressure balanced / temperature controlled unit - than MAKE SURE your adjustment ring inside your faucet is either completely removed, or adjusted to its maximum.

Google returns no results on "Nendecken" faucet. Please, double check its manufacturer's name and repost. Photo would be very helpful, too...

Sorry about my lack of info... here is a link to the exploded view of the faucet that I have:

http://www.plumbingspecialties.com/downloads/Kohler.pdf

Search the pdf for the following: KOHLER NIEDECKEN BUILT-IN MIXER
K-7000, K-7027-28, K-7076, K-7205, K-7224, K-7300-01

I don't think there is an adjustment ring on this model... so, when the cold water is on, it over powers the hot by at least a 25 to 1 ratio.

In the exploded view, Kohler lists "regulating scew" under #13, page 97. See if you can locate that one on your faucet and adjust it.

Also, remove seats and look for obstruction inside the faucet

Ok... thanks for the tips... I have tried adjusting that screw & it doesn't seem to make a difference...

As for an obstruction, I don't think that is my problem either, but I will check again.

I do plan on remodeling the bathroom this fall, so I think I will replace it with a brand new fixture and that should resolve my problem!