Thermostat Issues

[Shophound]

As for my house, yes the living room is Eichler like. Fortunately the
rest of the house has attic, to which I've add R30 insulation. But in
the living room I have planks that are stained and visible from below that
the roof sits on. I like the look from below. I suppose the best thing to
do would be to use spray foam insulation and put drywall underneath.
But I'm told that would be against code in Calif. right now, since attics
of any sort need ventilation. And it would not be a visual improvement.

I would not spray foam the underside of the vaulted ceiling. The stained boards and beams are part of the house's architectural appeal, likely. Is there an attic above the vaulted ceiling section, and is it accessible?

What I haven't read in any of your posts is a general comfort complaint, only a thermostat that is responding to the thermal lag of the wall when the thermostat setpoint is set up or down during setback operations. If the discrepancy bugs you that much, consider getting a cheap digital thermometer and suspending it from a string above the thermostat, so it will read the air temperature surrounding the thermostat, and not the wall. j/k

What may not be stated, but perhaps implied in your OP, since you mention the age and insulation status of the house, is a growing frustration with the costs to heat and cool this house. Maybe not. However, we're never going to have an energy source that's "too cheap to meter" so it only makes sense to look for ways to make the house easier to heat and cool, resulting in more denero in the wallet-o.

[a0128958]

Here's an example of how a 'modern day' tstat works, showing that the tstat reacts to a lot more than just air temp (such as rate of rise of air temp, and havinging a deliberate hysterisis gap):




In this case, this is a White Rodgers 90 Series Blue tstat, model 1F95-1271. Set point is 77°F.

Best regards,

Bill

[beenthere]

A Honeywell Vision pro will hold a lot tighter temp then that.

[cnpro18]

Just getting another post. Sounds like a mess.

[bobRitchie]

Yes I do like the exposed beams. I thought you figured it out exactly
when you mentioned Eichler. Like an Eichler my ceiling is what the roof
tar paper is directly attached to. And I have concrete shake shingles on
top. If my whole house was like that I might consider ripping off the roof
and doing the external spray foam roof. That's what the do to Eichlers
arround here. I'm surprised you have heard of Eichlers in TX.

I have suspended thermometers within inches of the stat. That's why
I'm convinced the stat is reading the wall temp. When the temperatures
have stabilized for a couple of hours the dangling thermometer reads close
to the stat. But when I crank it up or down for a couple of hours I see a
big discrepancy.

Clearly my living room is an insulation issue. But I don't see any fix there other
than building an attic. Which would be tens of thousands ... This is one of
the mildest climates in the continental U.S. If we didn't have ridiculous energy costs ( that increase geometrically with useage ) it would be no issue
at all. I figure that I spend about $800 a year on gas and elec for climate control. So cutting that by 15% would never pay back building an attic.
I have put new double pane windows on just for appearances. I saw maybe
a 5% reduction in utilities due to that. I did insulate where I have attic.
When I did the attic I had them do one small section of wall. ( There was
originally nothing in the exterior walls.) They made huge holes in the siding that I spent forever improving their patches. And my drywall nails poped in the area. So I considered the wall insulation experiment a failure. If this was
a cold climate the fact the house is all over a well ventilated crawlspace would be a problem.

Thanks for the input.

I have seen people with Eichler's actually just hang some breathable insulation stuff from the ceilings. But that really looks like hell.

[bobRitchie]

I think the Honeywell stat I have has too little of a hystersis.
I wish it was adjustable like the ancient mercury bulb ones were.
But what you show is way too much variation for comfort...

[beenthere]

The old mercury stats your talking about, would have about the same graph as that WR stat has.

Big temp swings can save money.
Tight temp swings provide better comfort.

[Shophound]

Yes I do like the exposed beams. I thought you figured it out exactly
when you mentioned Eichler. Like an Eichler my ceiling is what the roof
tar paper is directly attached to. And I have concrete shake shingles on
top. If my whole house was like that I might consider ripping off the roof
and doing the external spray foam roof. That's what the do to Eichlers
arround here. I'm surprised you have heard of Eichlers in TX.

I have suspended thermometers within inches of the stat. That's why
I'm convinced the stat is reading the wall temp. When the temperatures
have stabilized for a couple of hours the dangling thermometer reads close
to the stat. But when I crank it up or down for a couple of hours I see a
big discrepancy.

Clearly my living room is an insulation issue. But I don't see any fix there other
than building an attic. Which would be tens of thousands ... This is one of
the mildest climates in the continental U.S. If we didn't have ridiculous energy costs ( that increase geometrically with useage ) it would be no issue
at all. I figure that I spend about $800 a year on gas and elec for climate control. So cutting that by 15% would never pay back building an attic.
I have put new double pane windows on just for appearances. I saw maybe
a 5% reduction in utilities due to that. I did insulate where I have attic.
When I did the attic I had them do one small section of wall. ( There was
originally nothing in the exterior walls.) They made huge holes in the siding that I spent forever improving their patches. And my drywall nails poped in the area. So I considered the wall insulation experiment a failure. If this was
a cold climate the fact the house is all over a well ventilated crawlspace would be a problem.

Thanks for the input.

I have seen people with Eichler's actually just hang some breathable insulation stuff from the ceilings. But that really looks like hell.

I'm a fan of mid-century modern architecture, and live in a mid-century modern house. That's how I know about Eichlers. Additionally, there's the Eichler network, at eichlernetwork.com. Plus, I lived in California for 12 years (albeit I'm a TX native), and my family went there every other year when I was growing up.

Yeah, your ROI on building an attic over the vaulted ceiling isn't there, and IMO isn't the best approach. The spray foam roof seems more viable.

Still, the only thing I seem to glean from your post is that your thermostat temperature does not agree with a separate measuring device. It's possible the t-stat could be correct and your other thermometer is out of whack. I see variance among digital thermometers/hygrometers all the time.

[bobRitchie]

I know I would not be preserving the architecture by spray foaming inside.
And it would be silly to foam the whole roof, since only one room is that
way. And much of my roof slope is too steep for foam. I'm sure my
house was designed by a small time builder, not an architect. So its
enough Eichler like to offend the people who hate them, but not enough
for the people who like them.

I'm done careful experiments with different thermometers both digital
and mercury. And am quite certain that when the house is warming
up or cooling down that the thermostat can read typically 2, but
as much as 3 degree off what a thermometer dangling inches away
gives. When I'm at a level cruising altitude the stat agrees with
the dangling thermometer.

[a0128958]

... when the house is warming up or cooling down that the thermostat can read typically 2, but as much as 3 degree off what a thermometer dangling inches away gives. When I'm at a level cruising altitude the stat agrees with the dangling thermometer.

In order to avoid abusive and rapid cycling of the HVAC unit, I believe this is exactly how modern day tstats are designed to operate. The display reading on a digital tstat is only exactly representative of the ambient temp when you're "at a level cruising altitude" (well said).

Best regards,

Bill

[bobRitchie]

In order to avoid abusive and rapid cycling of the HVAC unit, I believe this is exactly how modern day tstats are designed to operate. The display reading on a digital tstat is only exactly representative of the ambient temp when you're "at a level cruising altitude" (well said).

Best regards,

Bill

I'm pretty sure what is happening is the delibrate programmed behaivor of
the stat. Its basically trying to make damn sure that the temperature doesn't
overshoot. But its overdoing it, and taking several hours to reach the
cruising altitude. It basically climbs rapidly to a point a few degrees less
than set, then gradually drifts up to the set point. I'd rather have a little
overshoot. Because what I've been doing for years is setting it a couple
of degrees higher in recovery, and then dropping it back manually when it
gets close. I'd like to find a stat that had a different characteristic, or
had a way to adjust the behaivor. What I'm trying to keep myself from
doing is designing my own circuit that I can tweak. I need to concentrate
on the engineering work I get paid to do, not silly projects like that. So
the question is what is the best choice of what's available in the market.

[jeff520]

I have a TC803, and have found that it does not tell the truth in an apparent (programmed) attempt to make me happy with its accuracy and performance.

The behavior I have observed is that whenever the ambient temperature is within about two degrees of the setpoint then the stat will tell me that the ambient temperature is at the setpoint.

I can catch it at this "little white lie" by making a large ( five degrees or so) change to the setpoint, and the stat will then display the correct ambient temperature. To see this, you need to catch the stat when the ambient temperature has either overshot the setpoint by a degree or two, or when the ambient is approaching the setpoint with only a degree or two left to go. In both situations the stat will display the setpoint as being the ambient temperature until you make the big change to the setpoint and then the stat will display the true ambient.

Had me fooled (dumb and happy) for a while just after the new system was installed. Then I checked the accuracy of the stat with a digital thermometer that displayed tenths of a degree and learned that the stat seems to have been programmed to report sucess with reaching the setpoint a little optimistically.

[a0128958]

... Because what I've been doing for years is setting it a couple
of degrees higher in recovery, and then dropping it back manually when it
gets close. I'd like to find a stat that had a different characteristic, or
had a way to adjust the behaivor. What I'm trying to keep myself from
doing is designing my own circuit that I can tweak. ...

If you want to continue doing what you've been doing, but in a more elegant and high-tech manner, you could replace your tstat with an AprilAir 8870 Communicating tstat, hook up an RS485 network cable from the tstat to a computer, and then be able to infinitely control and monitor the tstat in many ways, including those you may have not yet considered.

For much less effort, I believe you can replace your tstat with many of the existing digital models on the market today, 'tune' the tstat for agressive settings (via tstat configuration settings), and be quite happy.

Even my WR tstat that I illustrated earlier is 'tuneable' to be much more aggressive than what I illustrated. Mine is set for a Setpoint range of 1.2°F for Heat and 1.7° for Cool, but it can be set more aggressively to 0.6° / 1.2° if I wanted it that way. And it's further tuneable for how aggressive the 2nd stage kicks in.

And my guess is, the well regarded Honewell tstats on this forum have a lot more 'bells and whistles' to adjust aggressiveness, such that I'd be surprised if your needs couldn't be met.

Best regards,

Bill