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Re: Properly Sizing Primary/Secondary Piping

D T is the difference of output temperature versus return (input) temperatures. And no Gordy, it is not dependent on BTU but actual flow rates. 15000 BTU ar 20 DT is 1.5 GPM and 40K is 4 GPM. So I like to design my boilers to have a 25 DT. So 225,000 BTU is 18.5 GPM and 1 1/4 could do the job on the near boiler piping. 1 1/2 would be better on long runs as there is only .5 ft / 100 difference in head.

Henry,

How can you dictate a delta with out even knowing the boiler being used, or emitters being used?

I was giving a simple answer to the OP for starters. No idea of his knowledge. And I did include that those btu carrying capacities are in the 2-4 FPS flow rate. this all works together last I knew based on the universal hydronic formula.

To the OP get to know the universal hydronic formula well. once you understand it this all comes together.

Gordy

Re: Properly Sizing Primary/Secondary Piping

With primary/secondary systems, you can usually work with temperature differences that are much greater than the standard 20 degrees. That can save you a lot of money on pipe- valve-, fittings- and circulator sizes. I wrote a book that explains all of this.

DanHolohan

Re: Properly Sizing Primary/Secondary Piping

The proper way to size piping is by flow rate and not BTU. Get a Bell & Goddett System Syzer (it is free).
Here are a few sizes:
Iron pipe sizes
1/2 .8 to 2 GPM
3/4 2.7 to 4 GPM
1 3.3 to 8 GPM
1 1/4 7 to 17 GPM
1 1/2 11 to 26 GPM
2 20 to 50 GPM
2.5 32 to 80 PM
3 58 to 140 GPM

Never ever use the boiler connection size as the piping size! Don't use 35 or 40 F Delta T! The boilers that have Genonni type heat exchangers have very small passages like flat plate heat exchangers. The heat exchangers will block and fail. The past 3 years, we have replaced a number of installs by others that had insufficient pump and small piping.

Henry

Re: Banging noises in the wall/celing

Expansion noise. When the +180* hit a 55* pipe it will happen if there pipes are touching wood of not given enough space to expand. two options.
install a outdoor reset control on the system to match the temp to meet to the outdoor temps or open up walls....

kcopp

Re: A.O. Smith water heater. Big problems. No help. (JohnNY) Updated 3/27/15, 11:30am

I'll never know what the problem was there. I'm convinced there's an issue with the way my Cyclone was transferring heat to the water (after the burner) and I'm also convinced it's a problem that is not unique to the unit I installed and perhaps not unheard of at the factory.
Again, what I got from AOS was a replacement display panel that allowed me the option to turn off the modulation function, which, in fairness, was what I asked for.
That should have turned the water heater into a big dumb condensing unit like the old one was. Unfortunately, since installing that board and setting the burner to an on/off setting, the restaurant has seemingly never had less hot water. They tried it for two days and turned it off, switching to the building's metered water source.

I just got a text from the restaurant owner saying "Only good news!...temp holding steady at 140° after the mixing valve all evening".

The HTP Phoenix is working well.

Maybe, just maybe, I'll get some sleep tonight.

Again, thanks for all the helpful and supportive comments made here and to Mr. H for the prime real estate this post has occupied on The Wall.

I'm lighting a candle this headache is over.

JohnNY

Re: ? for Dan.

Thanks. Not change, but I'd add. And yes, I think there's more gas in the tank once I stop traveling to do seminars.

DanHolohan

Re: Rinnai R75LS code 12

I agree, check the gas pressure, and then clean or replace the flame sensor….You need to have the unit serviced as mentioned above…Pay attention to the burner assembly, a simple cleaning has fixed many of my service calls on the rinnai products…They stressed that during the factory training…You will also need a dual manometer

j a_2

Re: Rinnai R75LS code 12

You definitely need a qualified plumber hopefully factory trained to look at the unit. It could be several of the above mentioned issues. it may also have to do with the gas delivery. Faulty regulators at the meter can do this as well.

4Johnpipe

Re: Rinnai R75LS code 12

I believe that is a flame failure code. Have you had the unit serviced in that time? It could be a gas pressure issue, ignition issue, venting issue...a lot of possible items to check. If the unit has not been serviced in that time I would recommend having someone take a look at it.. If you look in the manual that would have come with the unit it gives you a long list of items to check...hope this helps..

lchmb

Re: Icesailor??

A few weeks ago, when we were in the midst of the A.O. Smith thread, John Cataneo asked Icesailor to please not post things on that thread that were moving it off topic. John was in a touchy situation at the time and trying to stay on point. Icesailor replied with what I thought were some particularly nasty remarks, which I removed. I then triggered a warning, which is an automated feature of this site. He didn't reply to that and hasn't posted since.

Trying my best to keep it civil here, guys.

DanHolohan