Comment on My customisable solar hot water system controller (project in progress)
roterabe@discuss.tchncs.de 11 months agoHmm, the heater element being controller disregarding your will is a bit of a bummer.
Thanks for clarifying, so you are indeed circulating the water itself, it’s not a separate line used as a heater. In this case you really are at the mercy of either your pump, pipe length, ambient temperature, insulation and/or sun intensity.
Have you monitored the temperature at the panel on the roof itself? Also, what type of insulation are you running on those pipes?
dgriffith@aussie.zone 11 months ago
It’s generic foam pipe insulation, approximately 3/4" thick.Originally there was also a 3-4 meter section of pipework from the collector output to inside the roof that was completely uninsulated, I’ve gotten that sorted.
I bought the place a couple of years ago and after replacing the seized circulating pump early last year I was pretty disappointed with the system’s performance.
At that point I put onewire sensors on the tank and lines on the ground level and measured it for a few months and didn’t see much heating at all from the collector.
I couldn’t get to the collectors for a long time, not having a three storey ladder, but I got suspicious after sunny + windy days resulted in very little heating. Finally got up there about three months ago to discover that bare section of pipe and insulated that.
Collector temperature I haven’t measured using the original analog sensor yet, I just let the original controller do its thing to get a baseline. But currently in a “warm” Australian spring the maximum outlet temperature at ground level is a brief peak of about 65 degrees C at around 1pm. Going off the circulation rate of the pump it’s probably 40 litres of water at that temp before it starts dropping back down in the afternoon.
Insulating that bare section of pipe improved performance but it’s still not fantastic, so now it’s time to drive the pump with my own algorithm and see if I can improve things.
roterabe@discuss.tchncs.de 11 months ago
Yeah, that seems like a good way to go. 65 degrees at ground level is what I’d also expect. My assumption up top would be close to 90/95 degrees. Driving the pump more often would be interesting.