Installing a low water cut-off on hydronic boiler.using secondar

Unknown

pressure fire boilers George. We have been referring to basic residential boilers. The LWCO in commercial water boilers would have to meet CSD-1 requirements and would therefore be manual reset. Residential boilers, as far as I am aware, do not have a provision for a low water cutoff when configured for water. It would always want to be in the supply piping as close to the boiler as possible with no valve in between. Regarding the materials from HydroLevel and McDonnell-Miller, I have their material also and as far as I remember, they do specify them to be installed in the boiler, but only for steam applications. I will check on this when I return to my office on Friday. I'm presently in New Jersey this week.

Glenn

boberg

Installing lower cut-off on hydronic boiler

Using secondary loop to pick 3 zones radiant fl. heating, DHW, and baseboard on the first fl . My question is this, Could the low cut-off fail if its installed above the boiler on the baeboard loop? Could the boiler pressurize and create a false reading with the lower cut-off,or will it shut the system before the boiler drains

Firedragon_4

I'm not 100% sure

if I understand the question, but all lwco OEM's recommend that the lwco be installed in the boiler or in the near boiler piping. It's also terribly important that they be in a space 1/4" from any metal or 'internal boiler pockets'. As long as that is doenI have never heard of your example happening. Many states are now requiring that a lwco be installed if there is any radiation below the top of the boier. Very common practice in Boston in the brownstones with gas boilers in the attics and 5 floors below.

Unknown

Low water cutoff devices

should be installed in the system supply piping as close to the boiler as possible. The 1998 International Code calls for a low water cutoff on every hot water boiler. There are only a handful of states currently enforcing this however. The latest two are New York and New Jersey. We, as a manufacturer of boilers, would desire that you use a 120 volt model on all installations, gas or oil. This will interupt the primary power source with no fear of incorrectly wiring into the low voltage wiring harness. Due to the fact that some localities and states do not want the LWCO in the boiler itself (hot water), we will more than likely NOT be providing a tapping for that purpose at this point in time.

Keeping it close to the boiler is the important thing. It is there not only to shut the boiler down in the event of a water loss, but will also provide protection in the case of an overheat or runaway condition where the high limit may be inoperative or has been overridden by incorrect wiring of a secondary zone or indirect water heater. In this instance the boiler will build high temperature and pressure and will pop the relief valve. This rapid loss of pressure with high temperatures may cause a steam pocket to occur in the top of the boiler and supply pipe. The LWCO will sense this loss of water and drop out the burner. Hope this helps.

Glenn Stanton

Burnham Hydronics

Firedragon_4

Check with the specific OEM

since I know for a FACT that at least two want them in the boiler. A lot of it has to do with section design and each OEM knows his product best.

As to codes, in the first three paragraphs of every code I have it states that OEM requirements supercede all others contained in that respective code. You didn't say where you are from but not every state recognizes the 1998 Version and in some cases like MA it's a mute point.

Unknown

Just curious George

Which OEM's are calling for the LWCO in the boiler. E-mail me with that if you get a chance. I've been told by several localities that the inspectors will not allow it in the boiler. Thanks.

Glenn

Unknown

Above the boiler

We want to see it just above the boiler, in the piping, with no valves or controls between the LWCO and the boiler. We want it to be a 115 VAC control, wired in before the boiler aquastat control.

Noel

Slant/Fin

Firedragon_4

Locations

Weil McLain and Smith in this neck of the woods Glenn.

I checked my manuals in the office and again last night on the Web and it hasn't changed.
http://www.smithboiler.com/html/19IOM.pdf
http://www.weil-mclain.com/FTP/80_Boiler_Manuals/Burner Manual 550-141-935.pdf

I also received (last year) training programs from both Hydrolevel and McDonnell & Miller and in the location photos and drawings for those two they show them in the boiler.

As you know many inspectors are either not up on the codes and are using old ones or just want it their way.
I encourage installers to 'do it by the book', but many don't want to fight city hall.

Mark J Strawcutter

low-water cut-off

is not a low-pressure cut-off.

I don't think it would be mislead by the situation you describe.

Mark

Firedragon_4

Okay!