Do outdoor resets and tekmar controls really $ave money?

Savings

Throwing a control on a boiler will give savings period. Rule of thumb is that for every 3 degrees you can run a heating system below 180 you can save 1 percent of fuel.

steam controls

Mark, the one thing you left out in your system description....it the system properly sized. All of the "old" steam systems out there are way oversized...a cycling control will definitely save $$$ as the system doesn't really have to run as long as it does. A cycling controller like a TEKMAR or HEATTIMER will save money....in a commercial job we did, we cut the fuel consumption a whooping 64% by installing a steam cycling controller.

better, but still plenty of room for questions

what boiler, what are the zones, what water temps are you set up for, etc.



it's an involved question. but basically if it's not designed passively with buffering and low temps, then the tekmar will likely pay for itself fairly quickly, provided it's configured well of course.

system sizing

It's great that your boiler and system are so well matched, Mark, but what about the size of the system compared to the heat loss. If you are right on on that score as well, your saving will be minimal, but if that system is oversized for the heat load, you can see significant savings and early payback for your investment.

ODR

Our house is HW and we have a CGa Gold, 82% Cat I boiler. The tN4 system actually cut our bill in half, and now pays us an average of $80 per month year round. (we have the 12-month equal pay plan with our gas provider) 

OD Reset controls are "Dumb and Blind"

I was installing stand alone steam/hydronic reset controls in commerical applications for thirty years. The controls work well and they do what the manufacturer says they will. Here is the problem! If the stand alone control is installed properly with the OD sensor located on the north wall of the building, the building is going to over heat. If the OD temperature is 30 degrees with no sun, the steam/hydronic control will cycle based on your reset curve settings. If the OD temperature is 30 degrees with bright sun, (remember the OD sensor is located on the north wall) the building will realize a passive solar gain and over heat. Heat Timer sells an internet based control system which utilizes OD reset along with space temperature averaging. All you do is set your day and night space temps and like that famous TV salesman says "set it and forget it". It is a little more involved than that! We are controlling over 150 apartment complexes over the internet and saving our customers on average 30 percent in fuel consumption.

PS - Try looking at Degree days and fuel used to determine energy savings.

 

North and South

That is a great question. When I first started installing the Internet based controls I was thinking the same way. It is very surprising to see the minimal temperature difference between North,South, up or down. Even garden apt complexes,hydronic or steam have relatively even temps. As a mechanical contractor, if balancing or specialty venting is required to close temp differentials that works for me. This is a great sales technique. Go into an apt complex with the owner. Sample approx 10% of the apts temperatures. My experience is you will get average temps (using stand alone OD controllers) in the high 70's to low 80's. Giving one or two apts 72 - 73 degrees to achieve a 70 degree average will work every time.