Heat Modeling (not Kate Moss)

gasfolk

Adding liquid thermal mass...

So if my house has fixed, high-mass, that may not be so desireable. It would be useful to have a simple way to measure thermal mass and to have a model to play with looking for adjustments that might improve comfort.

What if the capacitance and its related resistance could be varied?

1) What if your 1000 (or whatever) gallons could be pumped (like ballast on a boat) to an external tank (in the garage, on the roof, below the frost line, somewhere else) when low mass is desireable and restored when high mass is desireable?

2) Could the problems of high mass be overcome by some method of varying the resistance to flow in to and out of the capacitor? Hyper-insulate your house, but also install a heat dumping/charging system to reset the thermal mass? Waste of effort, or would that merely be a low mass house with an active solar storage system?

Thanks,

gf

Rich W

I agree with jp and constantin

up to a point. I think mass is always good, unless you like 10deg set-backs at night. GF,I like the idea of moving ballast. What about larger dia pipes and a valve controlling convective flow- kinda like a lock system on a river- let energy move itself. Without any historical data (that I know of), I don't know if it is worth the cost/effort.

gasfolk

You've probably seen this...

60 Ideas on How to Deal with Solar Gain in Radiantly Heated Buildings

Interesting ideas from a bunch of experienced folks. Can a simple model help to make sense of these issues?

gf

gasfolk

You've probably seen this...

60 Ideas on How to Deal with Solar Gain in Radiantly Heated Buildings.pdf.

Interesting ideas from a bunch of experienced folks. Can a simple model help an ordinary person to explore the pros and cons of these issues?

gf

Rich W

WOW


Ok, that's a lot of territory to cover. I can see a simple way to model a heat only system. Covering mass,heat gain/loss,recovery and redistribution of gain are not TOO difficult to mimic.

As far as the 60 ideas-, programmable controllers are much cheaper than just 4 years ago. I can see just going for the real thing instead of a mock-up. Programmed for time of day and rate of heat gain/set-point, you could move the heat to where it's needed. A few extra valves and sensors are cheap. Say the "solar" slab is 2deg above another zone- stop heating and dump the heat to other rooms. If they are already at set point then dump the water to storage/pre-heat for DHW. If that's hot too then dump to a heat sink under the basement floor to lower the delta T there. If all else fails, the controller can close the blinds or lower a shade to block solar gain...whatever you can think of. If you can define it, I can control it. There is a UL approved controller that I have programmed for this same type of system for a dozen houses over the last 3 years. Remote access,data logging and auto fault reporting to my Blackberry/ e-mail. Well worth the $400, because I can program it to be what I want/ the customer needs. It was intended to be an alarm system...all those "working outside the box" will never get it. You must know what is going on inside the box (house and controller) and deal with it. My apologies to anyone who uses that phrase.Most people I know use it as an excuse to beat the crap out of something with a hammer to "make it work".

gasfolk

Floating tempeature in modest range?

Hi JP,

Do you think high mass might tip toward beneficial if the occupants could understand and tolerate a bit of variablity in indoor temp, say 67 to 72 degrees (for example, and not counting intentional setbacks)?

With so many credible people recommending such different approaches, a model would be a nice way to try out some scenarios. I'm hoping that a simple model will also be feasible.

Best regards,

gf

jp_2

PLC

rich, which $400.00 PLC are you talking about, got a web site?

I'm looking to control a solar/heating system using a PLC, outdoor reset doesn't seem to be all the way there yet.

gasfolk

Google: \"thermal mass\" modeling

«a href="http://www.concretethinker.com/Papers.aspx?DocId=35">Benefits of Thermal Mass

An Overview of Modeling Energy Performance in Concrete Buildings

gasfolk

Google: \"thermal mass\" modeling

Benefits of Thermal Mass

An Overview of Modeling Energy Performance in Concrete Buildings

gasfolk

Google: \"thermal mass\" modeling

Benefits of Thermal Mass

An Overview of Modeling Energy Performance in Concrete Buildings

gasfolk

The Mother Load...

Building Energy Software Tools Directory

I'm hoping one or several of these software models may allow the analyses and answer the questions that most interest me.

Thanks to everyone for your comments, which helped me to better understand and clarify my questions.

gf

gasfolk

The Mother Load of Modeling Software...

Building Energy Software Tools Directory

I'm hoping one or several of these software models may allow the analyses and answer the questions that most interest me.

Thanks to everyone for your comments, which helped me to better understand and clarify my questions.

gf

Rich W

jp

Hi JP, it's called the OmniLT. Lots of add-ons to cover anything you need. Just stopped by for dinner- I'm on call. I'll look in later.

Rich W

ouch

My head is spinning- and I stopped drinking in 1983! Looks like lots of good info. Thanks GF.
Now, if only I had the time to read it all...

Mike T., Swampeast MO

modeling a home correctly using all the elements of design control theory (i.e. the flywheel effect, thermal short-circuiting, multiple insulation values, etc.) would quickly become a rather convoluted FEA excercise. I'm not convinced it's worth the effort, but that's just me.

You're probably right Constantin, but both you and Christian have given me an idea of such a model...

There's a bucket wheel with attached flywheel. It empties into a sluice that in turn divides into smaller sluices each served by a dedicated gatekeeper. The goal of the gatekeeper is to maintain the level in a bucket with a little hole in the side at just the level they want to maintain. There are however complications. The sluices leading to those buckets can be tilted--by the sun, the wind, occupancy load, etc. The gatekeepers can't see the tilt in the sluice, nor can they see the water coming out of the little hole. They have to wait for feedback. That feedback is related to the mass of the structure. It's all in the water if the boiler knows where to look for it and gives the little weatherman a helping hand...

Mike T., Swampeast MO

Thanks Christian! Truly enjoyed your drawings!

gasfolk

Making Sense of a Confusing Issue...

Hi Rich W,

One more link on this topic: Thermal Mass and R-value: Making Sense of a Confusing Issue

Sorry for the links, but after stumbling upon these explanations I wanted to share them. Besides as a thought experiment (which has explained a lot for me), do you see further benefit in puruing a circuit model of heat flow?

gf

gasfolk

Making Sense of a Confusing Issue...

Hi Rich W,

One more link on this topic: Thermal Mass and R-value: Making Sense of a Confusing Issue

Sorry for the links, but after stumbling upon these explanations I wanted to share them.

Besides as a thought experiment (which has explained a lot for me), do you see further benefit in puruing a circuit model of heat flow?

gf

gasfolk

Making Sense of a Confusing Issue...

Hi Rich W,

One more link on this topic: Thermal Mass and R-value: Making Sense of a Confusing Issue

Sorry for the links, but after stumbling upon these explanations I wanted to share them.

I will look into the controller you mentioned. Besides as a thought experiment (which has explained a lot for me), do you see further benefit in puruing a circuit model of heat flow?

gf

gasfolk

Making Sense of a Confusing Issue...

Hi Rich W,

One more link on this topic: Thermal Mass and R-value: Making Sense of a Confusing Issue

Sorry for the links, but after stumbling upon these explanations I wanted to share them.

I will be looking into the controller you mentioned. Besides as a thought experiment (which has explained a lot for me), do you see further benefit in puruing a circuit model of heat flow?

gf

Rich W

GF

Hi GF. As noted by all the posts here- the variables are numerous. While I think it would produce valuable information, it would also quickly turn into huge job to do correctly. Unless we can get guvmint/private money for full dedication to the project, I think it will have to wait.

As far as the controller, there are many others out there. I just like that one best. If you want to start from scratch there are the Basic Stamp2 and PIC chips. These give you total control with a steeper learning curve. I used the BS2 to make this monitor. It calls a pager and reports fault conditions of: Low gas pressure,No power to furnace,Low temperature,No power to sump pump,High water in sump pit and SOS for any alarm condition you desire. The only limit here is your imagination...

Have fun GF and thanks for the links.

gasfolk

Thanks Rich and everyone.

Best regards,

gf

jp_2

building the model

gasfolk, big herdle I see is the first model, you need real data to translate into an RCL circuit. then more intersting is deciding on a frequency.

so you need to "measure" your heatloss, not calculate it, measure your heat capacity, measure infiltration, etc....
need to also figure out your balance point, point where house drops below 65F and calls for heat.

sounds like a fun project. keep us informed.

Boilerpro_5

Thanks jp. Will do.

gf