Rinnai pressure problem

hvac-tech

Training & customer ED. Needed!!! In 2/05 or 3/05 IN THE C.R Mag. Pay back on going tankless is 25 YEARS!!! A Delta T 50oF makes only warm h2o. 90oF is to cold for a shower! A 10 min run time for a gas h2o heater to reheat the h2o in the tank is normal over a 24hr time line. That is only 0.6944 % how is that a LARGE LOSS!!! A 1" NAT. GAS line by the book can deliver about 300,000BTU's at < than 25'. A furn. with 100,000 input & a tankless with 199,000 input. Will need a new NAT. GAS line.

Thank's

Mike Pfluke

Pressure drop

We recently installed a Rinnai REU-25 instantaneous water heater. With one shower running all is well if a second shower is started the pressure in the showers drop dramatically. Does anyone have a suggestion as to what I can do?

Bob Sweet

Mike,

> We recently installed a Rinnai REU-25

> instantaneous water heater. With one shower

> running all is well if a second shower is started

> the pressure in the showers drop dramatically.

> Does anyone have a suggestion as to what I can

> do?



any idea what size the distribution piping is delivering water to your showers? At first glance it would appear to be a water distibution problem rather than equipment issue.

Bob Sweet

Mike,

any idea what size the distribution piping is delivering water to your showers? At first glance it would appear to be a water distibution problem rather than equipment issue.

[Deleted User]

Suggestion....

Don't take more than 1 shower at a time, OR boost the water pressure of you can to overcome the pressure drop of the HXer on the tankless. Tis the nature of the beast.

ME

John Reynolds

Is it a presure drop or a flow problem depending on the water tempthe units will choke down the flow to give you hot water

John

JackFre

Check these things

Have you cleaned the inlet water filter on the cold water inlet? After an install they typically need to be run and then cleaned to get pipe dope/etc out of the feed line. What is your entering water temp and your outlet set point. At 70F rise you should get 4.5gpm. At 80F it should be 4gpm. If your touch pad is white, you can hit and hold the red button then hit the green and release both. The display will show flow thru the unit to a tenth of a gallon. If the controller is silver I think the sequence is the up arrow and then on/off (check the manual). Also, check your gas pressure. The biggest mistake in installations nationwide is inadequate gas line sizing. If you have proper gas pressure, a clean filter and your flows are poor you could have a supply water pressure issue or possible a cold water flow control valve problem. You may also try Rinnai tech service at 800 621-9419 (make sure you have the ser #). You can call my cell at 617 834-8751. I can help you! You can go to www.Rinnaisolutions.com for a ton of tech info. Please let me know what you find!

[Deleted User]

Even in Leadville Colorado???

12,000 feet above sea level?

They need to include a clause about "Your milage may vary..." as it pertains to flow and rise.

Blatant statements like that WILL get you into trouble. I know, because I'm the one that usually has to explain to the customer that Paul Harvey doesn't live at high altitude...:-)

Proceed with caution.

ME

JackFre

Which blatant statement, Mark?

The one where I said I could help? The one where my personal experience with Rinnai water heaters differs greatly from yours? I suspect that every professional person working at altitude knows that combustion will be de-rated for altitude. Beyond that Mark, the information I gave and asked for is pertinent to discovering the problem being experienced!

[Deleted User]

The problem Jack...

is in the MARKETING of the product. Unknowing Joe and Jane six pack see the literature, buy the product then complain that it doesn't do what the maker says it does. And this is not specific to your brand. It happens with ALL of the atmospheric gas fired tankless manufacturers.

They neglect to tell the consumer that the output of the product changes with altitude. At the rate of 4% per thousand feet, ANY atmospheric fired appliance will lose almost 1/2 of it's capacity in Leadville Colorado, and 1/5 of it's capacity in Denver alone. I can appreciate your willingness to help. Your statement about output was made without what I would consider a critical qualifier. "At sea level, you can expect blah blah blah.." That's all...

No offense meant, just trying to keep things clear.

ME

Scott Gregg

One other thing

If they have plucked out he flow restrictor, that could contribute. My first guess is filter also.

STEVE PAUL_3

RINNAI PRESSURE DROP

You are experiencing the identical problem we are in the midst of solving. The Rinnai heater requres a minimun of a 6"water column of gas pressure to operate properly. If the gas pressure is less and the water flow is at full capacity, the water would normally run through the heater too fast to heat properly. There is an automatic control in the Rinnai that will throttle the water flow to a lower rate to compensate for the lower gas pressure. We had a static pressurre of 6" WC, with the Rinnai running and 1 faucet on, we had a reading of 51/4" WC, when the furnace was added the pressure dropped to 41/4" WC.
We are working with the gas company, they have replaced the meter with a larger meter and bumped the pressure up a little. It improved but they have to bump it up higher. I will let you know what the final resolution is. By the way Rinnai was very helpful with long distance diagnostics.

JackFre

We in the trenches...

Mark, if I could tell you how many times a day I explain that in New England you will never get 8.5gpm out of an R85, due to the cold ground water...I agree with you that we frequently have to deal with/shape/clarify marketing claims and amend the information to our locale. My friend, the rep in FL, and those in other southern markets do in fact get the high outputs due to the high ground water temps and marketing will claim those numbers as correct. It is one of the reasons Rinnai wants to have meetings to train dealers before they put them in.

Mark, I've enjoyed your posts on this site for a long time. Thank you!

[Deleted User]

Thank you Jack...

for paying it forward. Wouldn't it be great if we ALL lived in Florida:-) Or maybe Hawaii :-)

4" of snow last night.

ME

jim lockard

Alot of gas

one thing about the tankless heaters is you need alot of gas. Once you have installed a tankless heater check the gas pressure with all gas appliances in the home running. If the gas pressure can not keep up you need to make corrections. Best Wishes J.Lockard