Feed water check valve:

icesailor

I had an inspection of something I didn't do.

An issue came up. The boiler had been originally piped with a Watts combination 9D back flow preventer and 1156F fast feed hot water boiler feed that fed water to a M-M 51S LWCO and feeder. Because the boiler was running at 12#, it wouldn't add water when the boiler was running. I removed the 1156F. I know that commercial boilers require a Watts 009 backflow (or equivalent) but I figured to leave that for later. The inspector told me that I had to remove the 9D because the boiler water could back out through the reduced zone part of the floor. He wanted ONLY a check valve. Like shown in the below installation manual on Page 2, Figure 1.

 I don't argue with inspectors

He also said he didn't want the boiler fed in this location

<a href="http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/documents/2012/04/MM-315D.pdf">http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/documents/2012/04/MM-315D.pdf</a>

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kcopp

The boiler is....

a pressure vessel.. Technically it needs a back-flow preventer. A check valve (single or double) is not an approved device, unless it has the vent in the middle. If he is concerned about leaking then pipe it to a drain. Sometimes you can't win.

icesailor

009 Backflow

This is what is required.

A backflow inspector can put gauges on the test ports to see if they are working properly. If they aren't working properly, they order them repaired or replaced.

If you have big bear paws, the 3/4" ones are extremely difficult to repair with a repair kit. You need three hands with small fingers. 1" ones aren't so bad. You still need 3 hands usually.



http://www.watts.com/pages/_products_details.asp?pid=895

Eric_32

Sometimes...

you get one that knows more than the code.

I've always installed the 9-D on residental steamers with an auto feed.

Ones with a manual feed only (via ball valve/ stop and waste) do not require the backflow.

Like you said the commerical boilers have a 3/4" water feed and need a RPZ like the 009 or 909.

icesailor

Check Valves:

The McD&M manual shows a check valve on the inlet to the feeder. A 9D, 009 or 909 is also a check valve. If you install a check valve between a boiler fill and a 9D, 009 or 909, it will leak out of the vent because it needs the back pressure to act on the checks. Or so I have seen and thought.

Watts started making 9-11 combo units because do many were putting the backflow AFTER the fill valve. The McD&M like the Watts 1156f has an internal check but you still need the 9D, 009 or 909. I thought I understood the principal. Being told I'm wrong makes me want to learn what I learned wrong.

I had to install a second LWCO. I installed it in a tapping in the front of the boiler, provided by the boiler manufacturer. The 3/4" tapping is at the same level as the bottom of the gauge glass tapping's. When the alternate LWCO was being tested, the water level went below the bottom of the gauge glass. You couldn't see the water level when it finally shut off. He wanted the bottom of the gauge glass below the LWCO so he could see it. The boiler manufacturer doesn't provide a lower hole to do this. I can understand him wanting to know but what to do when the manufacturer doesn't provide one?

clammy

backflow n chk

As of recently we have not had town or city  inspectors say any thing but on our commerical jobs we have been told to install a check valve and  a backflow usually by the insurance company (commerical ) and not by the inspectors  a watts 9d is suffecient .I believe it is in the residental codes but rarely have inspectors say boo but we install a chk and 9d on all jobs where residental or commerical .It seems around here the inspectors rarely fail much unless they are new to the job and usually it is just a show of authority ,power and to make contractor return to go over things so they can make even less money .most of the time the whole permit inspection thing is a money grab by the towns and really ensure the custermer of just about nothing being they have no responcablity for anything including mis installed heating systems .Sorry if it sounds like a rant it may be peace and good luck clammy