Does your faucet have a pressure reducing gasket in it? We had one in a Grohe and when I contacted them they sent a different part. We also just removed them from shower heads.

I have removed the flow restrictors from all of my new shower heads...watch youtube, very easy. When we considered doing Rinnai in our addition, our plumber cautioned us against it...

Thanks, clt3, I have actually read on various message boards about contacting Delta for a different gasket and I plan to do that. But I think my real question is if I should install a whole house booster pump to my house since the incoming pressure is low anyway. Does anyone have this set up with a tankless?

I've had a tankless water heater for 17+ years. It was already in the house I bought. The showers and faucets (except not one of the two bathtub faucets) are the low-flow standard of that time. I have no problem with low pressure beyond the inherent design of the faucets, which I don't consider to be a problem. I don't have a recirculation pump. Why do you believe it's required?

I know nothing about this so take this comment with a grain of salt, but won’t a whole house booster just work the same on all your appliances and systems just like it would be if you had naturally good water pressure? How would anything act differently with a boosrer than it would if your pressure was good in the first place? Nothing will differentiate the source of good pressure as long as it’s not too high.

I guess I am trying to kill two birds with one stone. I would like better water pressure everywhere in the house, and am hoping that will improve the performance of the tankless water heater - which performs best when a specific gpm is being 'called for' from a faucet. The more hot water the faucet is asking for from the water heater, the quicker it arrives (with some caveats) but basically, my plumber has told me the reason I am not getting hot water as quickly at my kitchen sink as elswhere in the house is due to the low flow feature of my faucet. So this feature, coupled with my already low wtaer pressure, is causing a problem specific to this sink. I am hoping a plumber or someone with this type problem may be able to figure out my best solution.

To be clear, I do have the recirc device that Rinnai requires for better performance - and it works great - but that is not my problem. I am asking about a whole house water pressure booster that would be installed where water enters my house.

We just built a house, have really good pressure and I'm not very happy with the Rinnai tankless. We have 2, one at each end of the house. We also removed all restrictors. My kitchen faucet has good volume through it. We also had a recirculator added after we moved in and it helped a bit. Getting hot water is random and unpredictable. Yesterday I was handwashing some pans and the water was really hot. I turned the faucet off and a few minutes later my DH went to handwash a few other items. It took 15 minutes to get hot water to come out again. Didn't make any sense, so much for on demand hot water!!

Chispa - I think there is a switch or button or something on your recirculator that needs to be activated. That happened to us at the beginning - the unpredictability - and the plumber, who took another long look at the install info, told me the info regarding this switch is 'hidden' at the end or something like that. He has installed Rinnai before but says this is a new twist. Might give Rinnai a call.

@geegess, the plumber has been back a couple of times and everything is supposed to be set correctly, but this just happened yesterday. The plumber even added the wifi app so we can see what the water heaters are doing. When we had the kitchen faucet open full blast with just hot, the water heater app did not show there was any demand. We let our builder know and he'll get the plumber out here again. We are moved in, but still finishing up some items.

What is the minimum flow rate for your tankless water heater and what is the gpm of the faucet? Rinnai tankless gas water heaters need a demand of at least 0.4 to 0.6 gallons per minute of water flow through the hot side to ignite and 0.26 gallons per minute to stay in operation. I'd assume electric would be similar.

@geegess

You need to understand what's causing your water supply issues.

Do you have low static pressure or do you have a restricted supply?

You aren't going to fix a restricted supply with a pressure booster pump.

What is the static pressure (psi - when no water is being used in the house). I assume this is municipal water.

Jake - that is a good question and one I do not know the answer to. But it is common knowledge in our neighborhood that we all have low pressure. I actually have a booster pump on the irrigation system (separate meter) so I am assuming I could have one without problem on the house water.

So, it might be a good idea to get a pressure gauge and measure it.

This will screw on a hose fitting so, put it on your washing machine hookup or something since your irrigation is on a separate feed.

Following "Tom Hank"

The issue with a water heater at one end of the house and the demand at the other is a known issue. Having pipes in the slab, and a tankless heater, make it worse. Not having insulated pipes can make it unbearable.

Usually the bad design is the heater in the garage (at one end of the house) and the master bath at the other end. In one case on here, the person posting had no heat in the hot water left by the time it made it to the shower in the winter. It would eventually get "warm" if running the tub at 4 gpm, but not the shower at 2.5 gpm. The pipes in the slab weren't insulated either.

The right solution for your situation is exactly what you did -- a small tank under the sink that gets hot water there fast until the main heater takes over.

It's important to note the amount of water flow needed to start a tankless heater. Rheem has one of the lowest flow rates to activate the heater (0.4 gpm) and maintain (0.25 gpm).

geegees, the increased flow rate does not get heated water to the faucets more quickly because the tankless is working better ... it does so because the water as a whole is flowing faster, purging the standing cold water in the supply lines more quickly out of the faucet. The same effect would occur with a traditional tank water heater. It's a factor of the distance between the water heater and the usage point, not the type of water heater.