Bill W , question

flange

i have read about not using drastic setbacks due to flywheel effect, and i understand the concept. i guess in a lot of circumstances it makes sense, but i have a customer with a very large home. steam system, two pipe, with pnuematic controls. he has a stat in every room, controlling each rad. five of those rooms are utilizing day/night stats, with a setback from 71 degrees to 58 degrees. this occurs twice daily via a time clock and a dual pressure prv. the system was very old when i encountered it, and i more or less utilized modern controls in his ancient system. further mods were not possible due to the historical nature of this house. by doing this and dropping his pressure from a staggering 4 psig to 1 1/2 psig the customer has experienced approximately fifty eight percent reduction in fuel, and what he calls excellent comfort. his boiler is about 880,000 btu with a duel fuel gun. so i guess the question is: if (drastic) setback is so horrible why is my customer soo happy?

Mark Wolff

Setbacks

What you have effectively done is shut the heating system off all night (the house will not cool to 58 overnight most likely), hence the drastic fuel savings. I think it's a good idea; if the house is brick or new the heat loss will be slow allowing a nice cooler home during the night, but not uncomfortably so. I too see no reason in a setting as described to limit the setback point.

BillW@honeywell

Setback/steam

Setback on steam is controversial at best. Essentially, your client has a commercial system in his home...btw, I LOVE pneumatic controls, I think they are just as good if not better than some of the "Modern" stuff out there, for example, would you rather change a $10.00 diaphragm or a $500 electronic motor? I digress.

In most regular homes, the systems are effected by other factors like insulation, windows, homeowner lifestyles, building tightness etc. In some homes, a deep setback can cause overshoot due to the flywheel effect of the steam system, but in others, it may not. Some of the steam experts who frequent this site swear by setback, others swear at it. Yes, it can work, but it needs to be evaluated on a case-by-case basis. BTW, drop me an email if you're having any problems with that pneumatic system. The parts are still available, and I welcome the chance to "play" with pneumatics, just like Noel & Steamhead & MadDog like steam!

Unknown

I like p-neumatics, too!

I agree, on this one.

I think that you have a wonderful system for setback. One pipe steam is different than 2 pipe in that respect.

I worked with a system like the one you describe. The air lines had water in them. Once they were dried out, it worked flawlessly.

I love pneumatic controls

Noel

flange

hey thanks for the offer of help, but i am very familiar with pnuematics, having worked for honeywell for over ten years. just a little addendum, the five zones report to a honeywell load anylyzer, which operates a pe switch to start/stop the boiler. the new load analyzer is quite small compared to the very old solid brass contraption that came out of there. this is an old stone mansion, circa 1923 which still has the original operating one person elevator.oh and one other thing, the steam traps havent been touched for at least seven years and are still functioning very well.

Fred Robinson

steam and pnuematics

Keep both steam and pnuematics. Steam less trouble than current hydronic systems and the pnuematics are not obsolescent with each new product catalog.