coolinghvacplumbing
How efficient would it be to use radiators circulating with cold water, to cool house in summer?
Wondering if anyone has tried this, and how well it works?
I was thinking about H/AC in general, and wondering if it is possible to to leverage my actual system to get cooling in particular…
Anyways, all I could find was this, but it's advertising a service so not really credible in and of itself.
You don't have to worry about a heat pump being inadequate for cooling tasks, they are available in a large range of sizes. For really large buildings, they can be ganged together. 800 sf is a walk in the park for residential sized units.
I don't know the specifics of what determines when the backup furnace kicks in. IIRC, it is the combination of a lower thermostat set point and the outside temperature. It kicks on when the pump is not keeping up or it's too cold for it to run efficiently. I can assure you you will not be sitting for hours waiting for backup heat. No customer would sit still for such a system.
While it is true that heat pump heat is free, you are just paying to move it around, if you've had heat wave cooling bills before, you know moving heat around is far from cheap. Only a careful analysis of the various options, considering both operational and installation costs, as well as life cycle replacement, can you make a proper decision about which system is most cost effective. The correct solution will vary by small changes in energy costs and climate.
In cold climates, a ground heat source system should at least be considered because it will reduce or eliminate the need for backup heat. If you are concerned about your carbon footprint, do not forget most electricity generated in the US is by burning fossil fuels. Your footprint from using a heat pump will vary greatly depending on where your local power is coming from. Heat pumps make a lot of sense for many people, especially if they are investing in cooling equipment anyway. But everyone's situation is unique, so the best solution can be arrived at only after careful rational analysis of all the factors.
Here's a diagram of a hot water recirculating system
As I understand it, the idea here is that the recirculating system runs hot water around the pipework to keep the temperature hot near the faucets/taps. This allows for instant hot water at faucets/taps far from the water heater.
Even when no taps are running the pump should be actively maintaining the circulation as needed. It needs to do this as any unlagged pipes will cool the water in them if no faucets/taps are drawing hot water.
When the water near the faucets/taps is sufficiently hot, the "Aquastat" will turn the pump off.
Your power feed to the recirculating system should be via a timer, or other device, that lets the pump run whenever the "Aquastat" feels necessary. This should be "on" during any times of the day when you are likely to use the faucets/taps.
Some ideas:
You should be able to test this with a thermometer and a voltmeter if you can locate the "aquastat"
Best Answer
I think you'd end up running into a whole boat load of issues before you could even begin talking about efficiency. The first and most pressing being the rapid condensation that would occur within seconds of circulating the cold liquid (leaving you with a whole host of other DIY problems you'd need to work out). Which, I imagine would need to be somewhere between 20-60F below the ambient temperature of the air to get any significant cooling effect.
As for efficiency directly, if what I learned in PHYS160 about thermodynamics holds up, it should be exactly as efficient (heat transfer wise that is) as the radiators are at heating the air. But I HIGHLY suggest getting a second opinion from someone more versed in HVAC work, as the closest I've come to directly researching this is looking at data center cooling technology.
**More on datacenter cooling: http://searchdatacenter.techtarget.com/feature/Modern-data-center-cooling-systems-No-muss-no-fuss-no-waste