Shop temp

[Jeff-C175 7,202]

6 hours ago, Gregor said:

using 71 as a base temp,

 

(EDIT: I posted below before I saw the other replies! So you're good to go now!)

 

That base temp is not the temp you are setting the thermostat at.  Leave it at 65.

 

Let's say you run the heater for a week with NO setback.  Take the hours that it ran and divide that by the number of degree days during that week.  You get a number that represents TIME per DEGREE DAY.

 

Then do the same running WITH the setback.  Do the same division.  If it's a lower number it means the setback is saving runtime. 

 

You need to do longer periods than one day.  You have to average out the data because it does NOT take things like Sun versus cloudy days, which also has an affect.  WIND is another factor in heat loss and it can't account for that either.

 

The longer your sampling period, the more accurate the results.

 

You don't have to fool around with BTUs or anything else.  As long as you have run time and degree days you can do a fair comparison.

 

Edited November 24, 2021 by Jeff-C175

[Jeff-C175 7,202]

1 hour ago, Handy Don said:

Pursuing this and coming up with a feasible deterministic solution would be of terrific interest to building scientists and likely earn you a doctorate. Good luck!

 

They're already on it Don!  Have been for decades actually!

[Gregor 4,846]

6 minutes ago, Jeff-C175 said:

You don't have to fool around with BTUs or anything else.  As long as you have run time and degree days you can do a fair comparison.

True. That will tell me what, if any difference, there is in run time. But knowing the actual BTU and KWH usage and cost per unit, will tell me just what it's costing me to run the heater. Not that it matters much, I aint shutting it off. I'm not one for   I only have 3 trees, and I wanna keep them.

[Jeff-C175 7,202]

1 hour ago, Gregor said:

explain to my wife it does no good to turn the heat down at night, but I will be able to explain WHY ?

 

How are you with excel spreadsheets Greg?

 

The degree day data comes in a spreadsheet format already.

 

If you can figure out how, you can add your runtime data to that same sheet and even generate a pretty GRAPH that would really impress your bride!

[Jeff-C175 7,202]

10 minutes ago, Gregor said:

True. That will tell me what, if any difference, there is in run time. But knowing the actual BTU and KWH usage and cost per unit, will tell me just what it's costing me to run the heater. Not that it matters much, I aint shutting it off. I'm not one for   I only have 3 trees, and I wanna keep them.

 

You could add that data to the spreadsheet also!  You could have a pretty graph with multiple different colored lines!  That would be even more impressive!

 

By the way, that's pretty much exactly what I did a decade ago.  I knew I had to replace my boiler so I had to prove to myself that I was buying the correct size.  I also added insulation and wanted to know if the expense was worth it.  It was!  Paid for itself in four years!  But the savings replacing a boiler that was more than twice as big was impressive.  I heat my home now for about a third of what it used to cost!

Edited November 24, 2021 by Jeff-C175

[Gregor 4,846]

6 minutes ago, Jeff-C175 said:

How are you with excel spreadsheets Greg?

I'll work on that

 

[Handy Don 12,235]

41 minutes ago, Jeff-C175 said:

 

They're already on it Don!  Have been for decades actually!

Yep, I know that a lot of algorithms exist for this, but they all rely on assumptions or generalizations at large scales (i.e. all or most of a building over long periods). Site, continuous weather, seasonal changes, and structure-specific analyses require a lot of (generally not collected or even economically collectable) data on weather, construction, occupancy, etc. So far (to the best of my knowledge) BIM systems are still delivering good and relevant approximations only--and, yes, most of the time this is "good enough for government work".

 

One example is tree-shaded houses--when do the leaves grow out in Spring and drop in Fall? It makes a difference! How cloudy during which parts of the day? 

When I studied engineering, there was a lot of emphasis on responsible and relevant (and, yes, defensible) estimating, especially for those thinking of going on to be P.E.s.