A difficult house to control

[Pierre 1]

Hi guys. A very good friend of myne has this house. Its located on a hill crest, facing west, looking down on a 20 mile long (2 miles wide) lake. Ho! What a view. He tells me its a mediteranean design. 4 feet cement basement. Open spaces. West side wall are full of real big windows. His problem is heating. In winter his electrical heating bill is more than twice has much has myne The heating is all done through big BUH heaters in the basement. The basement is isolated on all sides except the ceiling which is the floor of the house. The floor heats up and ventillation circulates the floor warmth around the house. When the sun is up during the day and the heat gets in, the heaters stop. Around 4 o'clock when the sun sets the house starts to be cool. By the time the heaters do there job and the ceramic/cement floor gets hot enough to heat the rest of the house they are freezing in there. Around midnight it get so hot that they almost have to open windows. Cycle time is at the least very slow. We have no other controls but the thermostats in the main floor area. When its windy (in winter of course) he needs some heat but if clouds get in the way of the sun rays he needs a lot of heat. We can install a lot of sensors and logics but how would you guys suggest we attack this challenge.

[Sleepy Wombat 27]

Can you have a Winter manual override that will bring on the heaters say around 2pm in the afternoon and allow thermostat control from say 6pm ? All you would require then is say a standard Programmable timer or a an Omron Zen. With the Omron Zen you could have a number of varations in season adjustment available, the same could also be said for a programmable timer i suppose....Thats the most simple and chapest soln that i could come up with....

[Pierre 1]

The situation requires more judgement. I use to thinck that if a human being can control it by hand a PLC can certainly do it for him. But now this system is very hard to control even by hand. We stand in the house and look outside. Sunny. The temp. is minus 10 and there is no wind. We set the room temp to 24. Underground the heaters kick in and the basement temp. raises to 90C. By the time the room temp rises 1 degree we almost cannot walk on the floor. So we need to have a lower heating space temperature. Since the differential is less the exchange is also lessen. So if we want smnoother cycles we make them even longer. We need for this thing to work a lot of sensors. Outside air. temp. + chill factor + wind velocity + room temp + air space temp + heat exchange rate. Or is there a simpler smarter way to do this? We have all PLC + HMI + power sources we can use its only to use then in an elegent way. And of course increase the comfort.

[Shad 0]

I dont mean to sound obvious here but has he contacted the installer/manufacturer of the heating system and asked for suggestions. Sounds to me like there were some real miscalculations at the very least in the design of his heating system. I used to be a residential builder and have some experience with various heating systems and that just sounds like an awful set up in my opinion. If Im correct you are talking about a hydronic system and yes those do tend to require longer cycles to create a comfortable environment and the large windows would complicate the demands on the system but that should have been taken into consideration during the install. I know this didnt directly answer your question but it might be a useful place to start if you havent already tried this.

[Pierre 1]

Chad - This house was built only on the esthetic value of the design. But the design comes from the Mediteranée. It is in no way suited for North America. Once this is said we still have to deal with it. Originaly the owner/builder of the house was to use it only in summer and the heating was sufficient. So when my friend bought the house he did not have a set of electrical bills to judge of this situation. He is not concern about having been fooled cause this is not the case. Just the view is enough to make one appreciate the location and confort. This outweights any heating bill. BUT... this is not to say that we won't do anything about it. We have power and heat in sufficiant amount to be in the confort zone. The control is whats missing. And it need a pretty smart control system. Edited 25 Aug 2004 by Pierre