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Time Delay Switch Inquiry

I've seen some posts referring to this as a workaround to short cycling. That said, most replies refer to adding main vents and/or adjusting the Heat Cycle Rate of the thermostat (which i believe addresses a slightly different issue)



Right now, after the first cycle, subsequent cycles average about a 1 minute on / 1 minute off until the thermostat is met. Concern is mostly during the morning and eventing recovery periods. The house is kept cold at night and during the day so it has to climb in temperature a quite a bit.



Given my oversized boiler (55K needed with 145K supplied by a Weil Mclain EG-50 boiler), supply lines being only 3/4", and that I've adjusted the thermostat and added sufficient main vents (2 Gorton #2 & 1 Gorton #1 on a 30ft 2" Main pipe), the only solution that I've read about and seems to make a lot of sense is installing a time delay switch. That way, after it runs for a 1 minute and the radiators are hot, there can be a built-in delay of some kind (e.g. 10 minutes), before kicking in again.



Any recommendations on alternate solutions? If the above is the way to go, any recommendations on what to purchase, installation guides, etc.?



With short-cycling such a common issue, i would think there would be some common work-arounds (given that sometimes, as in my case, fixing the actual root cause cant easily happen).



thanks
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Comments

  • Clank ClankClank Clank Posts: 30Member
    Short cycling workaround

    Does anyone have experience with installing one?
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  • Mark NMark N Posts: 905Member ✭✭✭
    Short cycle

    There is a man who posts under the name MarkS. He used some type of time delay relay on his system. He has since built a controller to run his system. Do you have a Honeywell thermostat? You could try setting the cph to 2 instead of 1 and see how it works. That will reduce how long the thermostat calls for heat.
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  • MarkSMarkS Posts: 464Member ✭✭✭
    edited February 2014
    Time delay relay

    Hi Clank,



    About four years ago I developed a time-delay relay pressure cut-out and installed it on my system. The thinking was that if the boiler cuts out on pressure, then the system is (or should be) filled with steam. And if the system is filled with steam, then the latent heat should be left to do its job, and the burner shouldn't re-fire until then. After some experimenting I found that a 20-minute "off" period worked pretty well on my system.



    Here's a link to the thread with more discussion and wiring diagrams. If possible, I recommend you go with the low voltage solution. If your ignition control doesn't provide secondary 24 vac power like the Honeywell R7184, you'll need to use an external 24 vac adapter to power the pressure & relay circuit.



    In the original installation I used a vaporstat, but you don't need to go to that expense. Dwyer Instruments makes a low differential pressure switch that works quite well and can usually be found on eBay for a good price. The one I use now is a Model 1823-20 with an adjustable pressure trip point between 3" and 22" w.c. (1.7 to 12.7 ounces). If your system runs at a higher pressure, check the Dwyer catalog here to find a model that fits your pressure range.
    Post edited by MarkS on
    Links: EcoSteam | A Steam Odyssey | Odyssey 2 | Odyssey 2014 | A Steam Enthusiast's Outdoor Reset Control
    Royersford PA | 1890 one-pipe steam system | 3009 sf | 3 floors | 14 radiators | Utica SFE boiler
    Midco LNB-250 Modulating Gas Burner | EcoSteam modulating controls | 70 to 300 MBH |
    607 sf EDR connected load | Operating pressure: 0.5 oz | 4 mains, 135 ft | All Gorton vents
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  • Clank ClankClank Clank Posts: 30Member
    What I've been looking for...

    This is great. I already replaced the pressuretrol with a vaporstat a month or two ago so I'll be hooking it up to that. I'll look over the wiring compared to what I have and let you know how it goes or if I have questions. Think this is really going to help. Thanks again.



    I would think most most benefit from this.
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  • MarkSMarkS Posts: 464Member ✭✭✭
    Word of warning

    Don't use a primary safety limit control (the vaporstat) as any part of the time-delay control scheme. Control limits and safety limits must be kept separate. If something happens and your insurer finds out you modified a primary safety limit device they could deny your claim.



    Besides, the Dwyer switch is inexpensive enough. Just saw a new 1823-20 on eBay for $15.
    Links: EcoSteam | A Steam Odyssey | Odyssey 2 | Odyssey 2014 | A Steam Enthusiast's Outdoor Reset Control
    Royersford PA | 1890 one-pipe steam system | 3009 sf | 3 floors | 14 radiators | Utica SFE boiler
    Midco LNB-250 Modulating Gas Burner | EcoSteam modulating controls | 70 to 300 MBH |
    607 sf EDR connected load | Operating pressure: 0.5 oz | 4 mains, 135 ft | All Gorton vents
    · ·
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