A difficult house to control

[elevmike]

Sorry elevmike but maybee your experise is not in the heating industries.

I'm not at all insulted by your remark here becaus you've already been proved right. I had our own maintenance guys install a new HVAC system in our office. After much fiddeling around we finally called in the "experts". The problem was resolved by installing a booster blower. So much for that.....

With that in mind, I still see the problem as a delay in the rate of transfer from the heat source to the living space, and the mass of the floor as the barrier. Personally I would think that the water in the resouviour on the top side of the hydro-electric plant would make a better energy storage device for heating the house than the mass of your friends floor. If you can resolve the problem via strickly a control solution, then hats off to you. Obiviously your far more imaginative then I.

Regards, Mike

 

[Bitmore]

Well I'm glad nobody tried to tell me I'm all wet! I still think it is a good Idea to remove some of the BTU before it gets to the floor, and find another method for exchange. The only thing I missed was the floor does not have the heated medium flowing through it.
Now for options I have already, and did again, just suggest one. moon2

 

[Ricdel]

I think I'd try putting a sensor right on the floor's surface.

When the sun is going down, and it's associated heat is diminishing, the house may still be comfortable, but the floor would start to get cold first, since the room's warmer air would be higher.

Use the floor sensor to turn the heat in the basement on. The house may still be relatively comfortable from the sun's warmth, but the floor has started to chill.

When the sun is below the horizon, the floor could already be warming the house.

Have the heat come on when the floor's temperature is something below what the house's thermostat setting is.

I would just make sure the location of the sensor in the floor is an area that is shaded later in the day. (No direct sunlight)

 

[Peter Nachtwey]

First fix the heat exchanger problem

None of the solutions so far will work unitl you can get heat into and out of your heat resevoir faster. Your temperature system will lag way too much.

Next get a heat pump. Cool the house by pumping heat into the basement heat resevoir during the day and pump the heat out of the the heat resevoir back into the house during the day. You need an efficient heat exchanger to do this. Otherwise the heat resevoir sounds like it is pretty well isolated so the energy pumped into will stay there until the heat exchanger draws it out.

 

[Rod]

I'm hearing good things here.

My thoughts were that the the thermal transfer though an(assussmed) 6" thick pad of concrete on a 40x40' area would be 800 cubic feet of rock. That oscillation would break any PID - ESPECIALLY with the outside influences.

If it was MY house, I would set the underfloor heater unit(s) to 80F, to allow for heat loss thru the basement walls, measured at the underfloor substrate. That would eventually equalize the below floor and above floor concrete pad temps at an ASSUMED 75F.

THEN add above floor on demand radiant heater units to stop the wild temp swings. (You can NOT adjust for a sudden cloud cover with a 8 hour thermal mass transfer rate!!!)

And I would set one ceiling fan to blow upwards and the second to blow downwards to add to the convection currents.

If that doesn't work, I will be winning the lottery tonight and I can buy it and we can all have a place to 'Engineer'

Rod - the CNC dude

 

[XPierre]

Tom Jenkins
What you need is, I think, called optimized start/stop.
. You could replace the existing thermostat with another RTD and include night setback functions and so on as well.
. You could even use decreasing temperature trend in conjunction with the outside temperature to get a dead nuts pre-start.
… I think you can hae some fun and give the guy a system that works.


Sliver =>>The RTD is painted flat black. (talking ‘bout this bird house)
............
Pierre =>> The bird house will act as a Dead Leg, like in heat tracing difficult pipe systems. Its cheap but works great.


Substitute 10 watt light bulb for the bird, and you have a single analog input that can be tweaked to give you a reasonable, if not elegant predictor of heating load.
............
Pierre =>> The bird house is also a "Black body".

Peter Nachtwey
I think the situation can be made better but it can't really be fixed.
… your problem. The heat is NOT being removed radiated from the floor
…. You must find a way to remove the heat from the floor and get it into the rest of the house
… insulated the time constant of the floor may be on the order of hours instead of minutes.
First fix the heat exchanger problem

Pierre =>> Even his wife tought of that one. The design does not permit it.

...We have a problem like this in reverse where I work. When it gets really hot the air conditioner cools the air but the fan is not big enough to blow enough air over the cooling coils. Parts in the air condition unit start to freeze but that doesn't help get cool air to the working spaces. We need a bigger fan or bigger heat exchanger. So does your friend.
Pierre =>> I've done my fare share of systems like yours. Just to give you a hint. RELATIVE HUMIDITY. The fact that the coil freeze tells us that your fans are big enough. Push more water into this system and it will only freeze faster.

Bitmore =>> Peter brought up a good point, it seems the system is not sized wrong, just the method for BTU exchange.
Pierre =>> The fact of the mather is that it is perfectly sized. It was only installed in the wrong part of the globe

Elevmike =>> I don't think any amout of control can ever make up for a poorly designed mechanical system.
… With that in mind, I still see the problem as a delay in the rate of transfer from the heat source to the living space,
Pierre =>> We have tryed to increase the airflow but it was creating a disconfort to the people sitting under it.


Ricdel =>> I think I'd try putting a sensor right on the floor's surface.
Use the floor sensor to turn the heat in the basement on.
Pierre =>> We eventually will have something like this.

Rod =>> And I would set one ceiling fan to blow upwards and the second to blow downwards to add to the convection currents.
Pierre =>> This we did not try. Tanks.

So here it goes. I will soon install a "ACR Smart Reader Plus" 6 channel temp. recorder around his house. Its battery operated and will record a full month of variations.
In the mean time we will connect the BUH heaters to a small control panel with PLC and HMI. And yes Tom we will be having fun ... and MGD.

I will keep you posted on this one but the real cold weather is still a few months away.

 

[XPierre]

About the house !!!

In the Mediterane the day is hot and the night are cold.

This house fits the region perfectly. (So I was told)

During the day, you walk unto the ceramic floor and it is real cool from the heat it has given up the night before.

As the day passes it gather heat wich will be released during the next night.

I have experienced it (in our summer months) and it real nice during the day without any AC system, even when its 80F and more outside.

During the nights you walk on a floor which is perceived to be warm. Its also very confortable.

But it should have been built in Greece. Not Quebec.

 

[ltrail]

House with long thermal factor

Here's another suggestion. Artificial intelligence to gain knowledge of specific circumstances (cloudy+wind, sunny+very cold, etc.) Such database answers would call-up specific runtime temperature control. Perhaps the rate of rise or rate of fall of temperature included.

 

[Bitmore]

I'm gonna get long winded here and rude, so what,
First Peter suggested that the floor was causing the LAG and capacitative function, ie. to slow to warm, to slow to cool.
He's right.
Second, with my head up my brown, I thought it was one of those heated floors with pipes in it, and suggested to remove BTU's from the flow.
Then there were allot of others trying to help/understand, as I was.
Then after all of that, I still stand by my original idea, take some BTU's from the source and find some other way to re-distribute it.
After all of the disertation of all of the ideas, add infinitum, Peter and I were dead on. The BTU transfer problem won't be fixed without some other method of exchange.
You were still, in my opinion, "Sold a bill of goods" without a fore thought.
Good luck!

 

[DesertDog]

I remember older houses having grates in the floor for heating before forced air was popular. Sounds like this alone would make a huge difference. Hot air rises, a couple of well placed grates in the floor would let the heat rise into the house and also makes a good place to stand when you first come in from the cold, or to set a clothes drying rack (Childhood memories).

 

[Tom Jenkins]

(Childhood memories).

Our old leaky Minnesota farm house was "heated" by an oil burning heater in the living room and a woodburning stove in the kitchen. We had grates in the floor like yours. As kids, after being sent to bed, it was great fun to lie around the grate and spy on the grown-ups playing cards down below.

We obviously had a low threshold of entertainment in those days!