Steam heat-oil application question

HenryT · November 2009

Hi Everyone.

I have a quick question regarding a oil application, 1 pipe steam heat. My friend is purchasing a house and we did a walk through yesterday.

As we inspected the boiler, we noticed that the water site glass is completely filled with water and is shorter than the ones i normally see. Note That the boiler is also used to supply hot water in the house as there is no separate water heater.

Having said this, i have 3 questions:

for boilers that produce hot water, should there be constant pressure in the system? We noticed that the factory installed pressure guage was reading above 5psi even when tstat was turned off. Or can it be defective because the needle in the guage didnt move one bit for the entirety of the walkthrough? As for the glass guage, is it suppose to be completely filled with water? i thought it was suppose be be half way down? could it be its because this unit is used to produce hot water?

Any light shed on this will be much appreciated!

Thanks!~

Jamie Hall · November 2009

Problems...

First off, the pressure for steam should be less than 2 psi when the boiler is running, and zero when it's off. A steady reading over 5 psi isn't right, and suggests that the gauge isn't working properly -- it may be defective, or the pigtail may be completely crudded up. You do need a 30 psi gauge for code, and it should be working.

Second, there should be a marking somewhere on the boiler near the water glass which gives the normal working water level in the boiler. While it's usually about a third to half way up the glass, it might not be. Unless the glass is really weird, though, it shouldn't be full. There should be try cocks at the top and the bottom -- if you open the bottom one, you should get water. If you open the top (again, unless it's really weird) you shouldn't. It is possible, though, that the glass is misleading -- if the connections are plugged, it might read whatever it feels like. That should be fixed, too!

Third, the first thing I think of when I see too much water and a higher than normal pressure in a boiler with a hot water coil is a leak in the hot water coil.

Does the system make any heat? Did you try that?

I suppose the troubleshooting sequence would be: does it heat without much banging? If so, the water level can't be too far off. If there is an automatic feed, shut that off and shut off the DHW -- now can you drain the boiler (do this cold!!!) so that the water drops into the gauge glass? If so, turn the DHW supply on and keep an eye on it. Does the water level rise? If so, you have a leak in the coil (which may not be the only problem). And so on...

There are definitely problems here -- the question is, what are they?

nicholas bonham-carter · November 2009

over-filled boiler??

i think the recommended procedure for DHW producing steam boilers is to over-fill the boiler in the summer, when no steam is needed, and to restore the correct level during the heating season.

remember a picture is worth a thousand words here, if you think the sight-glass is wrongly installed.

another possibility could be an auto-fill valve not closing, or a leak between the DHW coil, and the boiler water itself. when you restore the correct level, see if you can close the valve on any auto-fill, so you can see if there is a problem. the boiler mfg's installation instructions should give the correct waterline height from the floor.--nbc

HenryT · November 2009

Thanks!

jamie/nicholas, thanks for your reply.

I will try to get pics tonight and upload.

Just so i know the lingo, DHW is direct hot water correct?

Where may i find this valve?

Brian_74 · November 2009

DHW

I think DHW = domestic hot water. There's a handy list of acronyms under the resources menu. I use it all the time.

Jamie Hall · November 2009

Thanks Brian...

I sometimes get carried away with the acronymns. Yes, DHW is domestic hot water. There should be a shut off somewhere between the cold water piping in the house and the connection to the boiler's heating coil for the domestic hot water. That's the one you want.

There will also be a valve on the pipe from the cold water piping to the boiler itself, but there are so many different ways to pipe this that I can't tell you where to look! That would be the one you would want to close to lower the water level.

NBC is right -- boilers are sometimes overfilled in the summer if they also produce your domestic hot water. Honestly I have never seen the point in this, and so I overlooked the possibility. Sorry... !

HenryT · December 2009

last question

Again, im asking this on behalf of my friend who has a boiler that also supplies the hot water usage in the house.

When the boiler is running, is there a way to control the temperature of the hot water? He's telling me that the water is scorching HOT when the boiler is running for heat....

Thanks!

jpf321 · December 2009

google: anti-scald mixing valve

there are many mixing valves available .. not all are "anti-scald" .. I have been thinking about installing one .. but have not yet so I have no experience first-hand. there is adjustable and non-adjustable. there are ones that are point-of-use (under sink/on shower) or ones that are at the supply end (near boiler)

if he looks around, he may have a manual lever for his mixing valve .. my manual valve is where the yellow tag is in this picture .. http://picasaweb.google.com/jpf321/Fitzgibbons400Boiler#5407071346748098530 .. my DHW leaves the boiler in the foreground copper .. the cold water supply is the background copper .. the manual valve with yellow tag connects the 2 lines and allows me to add cold water to the hot water .. normally I adjust this once during heating season and once in non-heating season

the theory is that one pipes the cold and hot water lines together into this valve. and it manages the outbound water temp.

Steam heat-oil application question

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