10-18-14, 03:45 PM | #11 |
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This should give you the idea, live monitoring of my ASHP (the graph is interactive so you can zoom in, scroll back in time etc.)
http://www.emoncms.org/ormston Notice how when heating dhw the power consumption starts low and rises as the tank heats up. Steve |
10-18-14, 05:44 PM | #12 | |
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To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her... |
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The Following User Says Thank You to NiHaoMike For This Useful Post: | buffalobillpatrick (10-19-14) |
10-19-14, 11:40 AM | #13 |
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Thanks Steve,
Your data shows about a 2% loss of HP efficiency for each *C increase of load temp. So keeping a load tank 15*C hotter to handle "design temp" winter night vs. a mild Fall day, would cost about 30% in HP efficiency. Last edited by buffalobillpatrick; 10-19-14 at 01:20 PM.. |
10-19-14, 08:24 PM | #14 | |
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The amount heat needed to raise a slab (it can be low mass as well) is considerably more than that needed to keep it a degree or so from the setpoint. We are wanting to have a system respond quickly when asked and the HP is not as capable of it compared to a gas boiler. It is all about expectation. If you don't mind using the straight electric or gas backup to do the fast injection of heat, then you can use the setback but if not, I would not because it will take a long time to heat up with just the HP, especially when it is colder out and heat load is closer to the HP capacity. |
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10-19-14, 08:32 PM | #15 | |
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There are saving to be had for sure. With boilers, the industry sort of agrees on a 10% fuel savings. I don't see why an ODR motorized mix valve just for the floor loops would be an issue. The tank would be depleted more slowly so the HP would not come on as much. |
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10-19-14, 09:10 PM | #16 |
Supreme EcoRenovator
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That's my objective in this situation. For the new hack, I'm rigging up a small outdoor air source unit to a water cylinder, much like the diy water heater heat pump. The water cylinder will act as a buffer or heat store for space heating via passive or forced air radiators. Rather than having a bang-bang thermostat directly sensing the indoor air, the odr demands heat pump operation based on the tank and outdoor temperature. When the zone is warm enough or not in use, the flow can be cut off. Meanwhile, the tank will radiate some heat on its own to offset the natural loss.
The main goal is to have long outdoor unit cycling and more even heating of the zone. |
10-19-14, 09:15 PM | #17 | |
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10-20-14, 03:22 PM | #18 |
Supreme EcoRenovator
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It looks like this one will be a 8 or 9kbtu rotary compressor (scavenged from a window ac unit) rigged to a large outdoor coil. I believe it is from a 2 ton air handler, maybe 2 1/2 ton. If the included txv doesn't hunt, it will be run stock. If it does, I can swap it out for a smaller one.
Defrost will be reverse cycle, run through a cap tube. I'm going to start off with the one from the ac unit and shorten it if I have to. With a hot water cylinder as a heat source, I'm not sure how much flow I will really need in order to defrost quickly. |
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