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Weekly Water Addition by Automatic Water Feeder

Hey Everyone,

We have 2 buildings: one with Weil McLain 680 Boiler and the other with a Weil McLain 880 Boiler. Each building provides Steam heat for 16 units (4 units per floor with 4 stories). One building is all 2 bedrooms and the other is 1/2 two beds and other half 1 beds.

We have water meters (measuring cubic feet) placed right after each automatic water feeder. I blow down the LWCO on each boiler about once a week. I don't let a ton of water out when I blow down the LWCO, just enough to flush out any gunk. Usually have the valve open for only about a second or two seconds at the most (hopefully that's enough, but please tell me if not).

I understand that the water loss from the system should be 0 cubic feet in ideal conditions plus whatever is being blown down by the LWCO, but I have never seen a building of this size in absolute ideal conditions.

I'm wondering what I should expect the water loss per week (including blowing down the LWCO) to be in a building with those size boilers and number of apartments. I know all buildings are different, but I'm just looking for a ball park estimate (Like 1/2 Cubit Foot per week? 1 Cubic Foot? 10 Cubic Feet? etc.)

Any ideas? Or if you are in a building of similar size, what is your usage?




  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    Blow-Down and Makeup Water

    If you have a float-type LWCO, it should have instructions for blowing it down. There are two reasons for doing a blow-down. Keeping sediment from accumulating under the float and preventing its movement, and testing the unit's operation, so you have let out enough water when the LWCO turns off the burners. They should re-light almost immediately after you close the valve. If the burners don't cut out when you open the valve, the LWCO is faulty.

    If your automatic water feeder has been installed correctly there should be a bypass valve. This valve should bypass not only the feeder valve but also the meter, so water added by opening the bypass valve won't register on the meter. This allows you to replace the water lost during a blow-down without affecting the water loss indicated by the meter, so the reading on the meter always reflects water lost from the system during normal operation. If your plumbing doesn't allow this, you need to subtract the blow-down water from the amount shown on the meter.

    If you're doing weekly blow-downs and topping up the boiler, the water lost during normal operation should not be enough to cause a low-water condition and activate the water feeder. The only water being lost should be that lost through residual vapor in the air that's vented at the beginning of each heating cycle. That's not a lot of water even in a large system. If you're losing slightly more than this you probably have a situation where water is spitting out of vents (usually cause by high pressure or incorrect pitch or other piping issues) or leaking from valve packings. If you're losing significantly more you may have other issues, like leaking radiators or leaking returns.

    Unless the system is drained at the end of each season you can often tell where to look for leaks by whether you need to re-fill the system in the fall. Leaky returns keep leaking all year round, but radiator and steam piping leaks will only leak during operation.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • Jeremy_16
    Jeremy_16 Member Posts: 113
    Water Usage

    Thanks for the response. I do have a bypass that can add the water back without passing by the meter, but I usually don't close off the automatic water feeder so the water that gets added back passes by the meter. I guess that's not the ideal way of doing it, but that's what I've been doing. If I add it back manually, I assume I would just close off the route of water from the auto water feed and add water back to the center of the gauge glass through the bypass, right? Then open the pipe back up to the autowater feeder, correct?

    Without subtracting the weekly blow downs, the amount of water added to each building system is about 1/2 of a cubic foot per week per building. I'm pretty sure there are no leaking returns (I think the buildings would be losing a lot more water if there were an active leak). I suppose there could be some steam escaping through one or two leaky vents, but unless a tenant reports it, it's hard to know.

    Does that amount of water loss including blowing down the boiler seem like a problem? Or about normal?
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,849
    It seems like a lot to me.

    Even if you were letting out a quart every time you blew it down that still leaves 3 1/2 gallons unaccounted for. That's a lot of water to lose in a week. You shouldn't be losing that much in a season.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,314
    check your returns

    If this is like most Boston buildings I have looked at the return need help. Are there recievers pumping the condensate into the boiler? I so are they leaking? or over flowing?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Jeremy_16
    Jeremy_16 Member Posts: 113

    Yes, both buildings have boiler feed tanks and pumps. The returns connect to the tank. When the water level in the boiler is low it calls for more water from the feed tank. I didn't install the tanks; they were already in the building.

    One tank is brand new as of this summer (old one was leaking because it rusted out at the bottom and needed to be replaced). The other one seems to be in good shape. Neither are overflowing. I think I would notice because it happened a couple of times with one of the tanks a few years ago. We ended up putting a pressure reducing valve on the water line from the city to the tank and that fixed the issue.

    I can't see all of the returns because many are beneath the floors. What I can see is not leaking though. Boilers are not leaking either. Tanks aren't leaking. No one has reported any radiators leaking (there are about 40 rads in one building and 50 in the other). Could enough vents be letting off steam vapor or leaking to account for that much water loss?

    If the returns were leaking, wouldn't I be losing way more water? Strange that both buildings are using about the same amount of water and have a similar number of radiators. What do you think? Does anyone else live in, own, or manage a building of similar size that measures the water usage?

    One more thing: until my first posting of this thread, I thought I was using way less water because apparently I was reading the meter incorrectly. I thought the decimal point on reading the cubic feet was between the white and black numbers on the picture below. Meaning I thought it read 198.0763 cubic feet. Then recently I asked someone else and they said it should be read 19,807.63 cubic feet. Is the latter number correct? Just want to make sure. Thanks.
  • steamedchicago
    steamedchicago Member Posts: 72
    edited November 2013
    water meter dial

    One complete turn of the hand is a cubic foot.  The odometer part reads in complete cubic feet.  So 19,000-whatever is correct reading.  The two black digits are black because most water utilities bill in 100 cubic foot increments. 

    A cubic foot is 7.48 gallons.  So if you're losing 0.5 cubic feet, a week, that's 3.25 gallons.  You're not loosing that as steam from properly working vents on 50 radiators.  It's about a cup a radiator a week.  A radiator can leak a lot more than that before a tenant notices or complains if they notice. 
  • Jeremy_16
    Jeremy_16 Member Posts: 113
    radiators are the problem?

    So you think some of the radiators may be the problem as opposed to the returns? What's the best way to trouble shoot this? If they are leaking, would it be from the vent (like steam escaping?) Would it be very obvious or practically unnoticeable unless you put your hand over it?

    I can go through apartments when the boiler turns on and check all of them. I'm sure they aren't all leaking, but it's possible that a few could be.

    I can also e-mail tenants to take a look at the radiator vents and report back any issues. I just need to know what to tell them to look for. Any advice is appreciated. Thanks.
  • Steam leaks

    Many tennants think that leaks are normal in steam heating, and so won't report wisps of steam they see as long as it is not dripping.

    What is your actual pressure when the system is running. If the pressure is spiking, then the packings will leak. You should be able to heat using 12 ounces max.--NBC
  • Jeremy_16
    Jeremy_16 Member Posts: 113

    Pressure slowly builds when the boiler starts. I observed it yesterday. It ran for about 18 minutes and the pressure climbed very slowly to about 6 or 7 ounces (I bought a gauge that you recommended a few years ago: 0-3lbs). It never climbed over half a pound.

    Both buildings have been heating well, but I haven't observed the pressure in either building build up very much (at least according the low pressure reading gauges - which I assume are working correctly). Is that good in this case?

    Do you think that I could have a few apartments with wisps of steam escaping that add up to the water loss I am reporting? If I had a return leak, I would imagine I would be losing a lot more water. Also, I have had the same water loss (about half a cubic foot per week) for over 2 years that I have been recording weekly measurements. Before that it was also about the same, I just didn't record it as meticulously. If it were a return leak, I would imagine it would have gotten worse by now, right?
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