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Slower Vents vs. Replace Radiator Covers? Nerding out here.

cnjamros Member Posts: 76
Ok, so I'm in the last mile of getting upstairs and downstairs balanced, to the degree, in my one-pipe steam system.

After super-venting the one problem radiator (which you can read about here: https://forum.heatinghelp.com/discussion/169569/vent-suggestion-replace-varivalve#latest ), the under-radiated upstairs is one degree cooler than the well-radiated downstairs.

After the first couple heating bills of the season (yikes!), I removed all of the radiator covers in the house to unleash the full efficiency of my system. I've also increased to 3CPH because of the new responsiveness of the system.

It seems to have worked, as I am now using fewer therms per "heating degree day" based on my obsessive calculations (more on that in another post someday).

My first floor radiators have MoM #4s, across the board.

My upstairs radiators have MoM C or D, depending on the room and style of radiator.

INCREASING the venting upstairs isn't really an option, due to the one problem radiator that has post-renovation-longer-runout-than-designed-its-a-long-story-dont-talk-about-it-in-front-of-the-kids issues. (see link above).

So, I'm thinking about how to trim back a degree from the downstairs rads. But I don't want to lose any of the efficiency I've gained.

I'm thinking of two options:

1. Replace some of the radiator covers to stifle the heat slightly.
2. Downvent even further by getting VentRite #1s for the downstairs, setting them as low as possible.

The Ventrites are a pricey proposition... not in the long run, if I keep the efficiency, but all you steam tinkerers out there know what I mean... it all adds up when you're "hobbying" like this.

The rad covers would be easy, but it a weird way I'd be admitting defeat. :-)... and also spending gas to generate heat that I then trap in a box.

Also, if I end up balancing with those existing covers in place, I negate my next obsessive project of "designing the most efficient, yet visually pleasing, radiator cover based on that old diagram that we've all seen on this site and stared at wondering how it's possible to get 110% efficiency out of a radiator".

But if I downvent, am I then running the boiler longer to fill the same rads?... thus using more gas anyway?

Anyway, I know I may be splitting hairs... but this is fun, so I'm taking opinions... Re-cover, or re-vent? Which is most energy-efficient?


  • jumper
    jumper Member Posts: 2,208
    Well if it's fun then enjoy. I'm impatient so I go for covers.
    EBEBRATT-Ed Member Posts: 15,334

    Hate to say this but if your within 1 degree you need to find something else to work on. The one radiator with the longer run vent the inlet side of the radiator
  • Fizz
    Fizz Member Posts: 547
    @cnjamros , you said you now have t-stat setting at 3chp, what kind of t-stat do you have?
  • ChrisJ
    ChrisJ Member Posts: 15,468


    Hate to say this but if your within 1 degree you need to find something else to work on. The one radiator with the longer run vent the inlet side of the radiator

    Not necessarily.

    I've done better than that but it took a few years. :p
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • cnjamros
    cnjamros Member Posts: 76
    @Fizz I have a Honeywell Vision Pro. Remote sensor in upstairs bedroom (the one with the questionably vented radiator). I was using a remote sensor in the main living area as well and averaging the two. However, I was getting too much overshoot... by the time the room heated up to temp, the radiators were too full. Now I'm using the main stat sensor (which is near one radiator) in the average instead of the downstairs room sensor... removed the radiator cover near the stat so that it's very responsive. That, coupled with the narrow temperature margin of 3CPH basically allows the thermostat to be fulfilled RIGHT when heat starts coming off the rads... allowing the house to flywheel up by only a degree or so, keeping the temps pretty consistent. I'm finding that, with 3CPH, the mains stay warm and I'm getting full mains within a minute or two of firing on each cycle. When I went down to 2CPH, I saw my efficiency go down a bit... which I'm guessing was because of reheat time because of longer time between cycles. It's worth noting, however, that my measurement of gas used is pretty coarse... I'm reading off the gas meter and it's either 5, 6, or 7 therms per day... no sub-units. I'm relying strongly on the longer-term averages here. :-) I don't have anywhere near the precise infrastructure of @ChrisJ hah!
  • Fizz
    Fizz Member Posts: 547
    Well done! Thanks.
  • gfrbrookline
    gfrbrookline Member Posts: 753
    My building is very well balanced and have had good luck with 2cph. I may try 3cph and see what happens. We do spend a lot of energy reheating pipes with lower cph's. Insulation is important and made a huge improvement in my system.

    I think people need to understand that if you have a well balanced system the radiators do not need to heat fully with each heating cycle to maintain the temperature of the building and we may gain fuel savings by tightening up the temp swing. It can take a one pipe steam system a long time to recover from a .75 degree fall back on a constant 1cph tstat setting, 2 or 3 chp will keep the pipes warm and not allow the building temp to drop that far so shorter boiler run time overall and if oversized less cycling. They key is balancing the venting of the mains and radiators.

    The problem is most systems aren't balance or insulated properly.
  • gfrbrookline
    gfrbrookline Member Posts: 753
    I also think 3 cph on a well balanced and properly vented system will be closer to how coal worked, the pipes and the radiators will be warm all the time but will only heat fully on extremely cold days as the system was designed to work.
  • gfrbrookline
    gfrbrookline Member Posts: 753
    Tried 3 cph for a day, the radiators closest to the boiler heated and the ones furthest away were colder, 2 degree imbalance. Back to 2 cph. It was worth experimenting.