Heating Help

Do outdoor resets and tekmar controls really $ave money?

I am certain that they save some money, but has anyone done any analysis or want to share what they have saved. I have heard numbers of 20-40% savings with them, and am wondering if they rally can make that much of a difference.I have been pricing out the tekmar 400 tn2 control with their thermostats and they sound like they can make an impact, but I guess i am wondering how much real money since i can eaasily spend $1500 on the controls and tstats.

I Believe

I heard those numbers too .. First the comfort level goes up. You don't get the hot cold Heating cycle. It just feels warm and even.. Where they save is in system loss , the cooler the system the less you use, The hotter your system the more you loose. Why heat it for the coldest day of the year all year round..

Once you spend the money you will be glad you did and it will pay for it self.. How fast depends .. Conseritive speeking ... I would say three to five years. The larger the home the faster the return .. Solid number no , just looking back on the ones I have installed..

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.

yup

we finished one this fall for a small school. they wont tell me what their fuels bills were, but did tell me they saved twelve hundred the first two months over the old 180 degree system.  

What about steam boilers?

How does this apply to a 1-pipe steam system that has been "greened" as much as possible to Dan's recommendations? That is, the boiler is sized to the load, the mains and radiators are adequately vented, the mains and near-boiler piping are insulated, and the operating pressure is below 4 oz.

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.

Sizing

Al,in my case the boiler is rated at 633 sf EDR and the load is 607 sf, so it's only about 4% over. I understand how these controls can work wonders on a oversized boiler. I'm hoping to understand what could be expected by installing an outdoor reset control on an already optimized system.

"it depends"

is always the right answer.

huge savings are often possible with intelligent control. A lot depends on "compared to what"?

MANY systems benefit from better control. But not all.

Compared to

the same system (properly sized, vented, insulated) controlled by a setback thermostat, with 7 night setbacks and 5 daytime setbacks per week.

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.

Mine is a steam system

not hot water, so no zones, water temps, or buffering. System stats are in my sig.

then totally ignore me

I know nothing of this "steam" you speak of ;)

So What You Are Saying Is (Steam Haiku)

Overestimate
Knowledge of Steam and Swimming
Same Consequences

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.

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.
 

Solar gain and temp averaging

I understand what you are saying about the north side outdoor sensor and the solar gain on the south side. But even with the multiple indoor sensors for temp averaging, won't the apartments on the north side be cooler than the south facing ones?

So "on average" the apartments will be comfortable but the south facing ones will still overheat, and the north facing ones will be cooler than the others.

I can't see any way around this unless there is some form of zoning, or you use TRV's  on the warmer apartments.

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.