phigment
Member
Last night I finally got my preliminary monitors setup for my Rheem ASHP. I logged some data points from midnight to about 11am (after we had 3 showers). Here's the graph if anybody is interested:
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If I'm reading correctly, the tank has a heat deficit it will try to make up during the next power use period.Here's the graph
OK, that is awesome. How did you get that data?Last night I finally got my preliminary monitors setup for my Rheem ASHP. I logged some data points from midnight to about 11am (after we had 3 showers). Here's the graph if anybody is interested:
View attachment 464238
The power co-op that provides power to my location agrees, they hate them, and you do not realize any savings when they get through with the service requirements and billing. I real deterient to electric tankless, gas is o.k. from what I know, (scaling ???) but I personally love my Heat Pump Water Heater and it helps cool my garage.This cropped up on my Facebook feed... not sure if it was intentional but it looks like they're fishing for prospective model 3 owners...
What really irritates me is how they take advantage of general ignorance around water heaters. 99% efficient sounds good to the lay person but that's a COP of <1 which is TERRIBLE from the perspective of a modern water heater. Heat Pump Water Heaters START at ~2 and go up from there.
Besides low efficiency... tankless heaters are BRUTLE on the grid. No one is going to schedule their shower around off-peak hours. You can use a heat pump water heater to store energy and schedule it to heat water during off-peak hours. Some tankless heaters can pull up to 18kW when heating water. It doesn't take many simultaneous showers to really start adding up.
Please have a talk with your power provider first when considering using electric tankless, they are a problem.I have had a Takagi gas tankless water heater for over 5 years and it has worked well and reduced my NG use. I can't provide any hard numbers.
In the future I plan to replace it with either a heat pump or an electric tankless but haven't done much research yet. This thread is interesting.
I have a simple python script that connects to the econet service and parses out the temperature data. I could also query their power usage, but I have a separate power monitor connected to the heater to give me accurate readings.OK, that is awesome. How did you get that data?
Please have a talk with your power provider first when considering using electric tankless, they are a problem.
My house is one of seven 200 amp services on a 25 kW transformer. I keep thinking that the power company should upgrade it but I guess they're fine until it blows up.Please have a talk with your power provider first when considering using electric tankless, they are a problem.
Last night I finally got my preliminary monitors setup for my Rheem ASHP. I logged some data points from midnight to about 11am (after we had 3 showers). Here's the graph if anybody is interested:
View attachment 464238
It is possible to put them in eco mode via a menu. The one I looked at required 240v/30a circuit. I don't recall the wattage of the elements or the draw of the heat pump. You still need to size the circuit for the full power draw listed on the appliance.I'm very interested in replacing our 12-year-old gas water heater with one of these HP Rheem units. Is it possible to force the resistive heat elements to stay off? Am I reading your graph correctly in that the unit draws less than 500W of power when heating? What is the amount of power draw should both resistive heating elements kick in? What is the breaker size required? The Rheem website claims only 1 back-to-back shower, but you've reported doing at least two. Looking for feedback on your experience with this.
Thanks!
For this unit there are multiple modes of operation. The app lists ("Off", "Energy Saver", "Heat Pump", "High Demand", "Electric").I'm very interested in replacing our 12-year-old gas water heater with one of these HP Rheem units. Is it possible to force the resistive heat elements to stay off? Am I reading your graph correctly in that the unit draws less than 500W of power when heating? What is the amount of power draw should both resistive heating elements kick in? What is the breaker size required? The Rheem website claims only 1 back-to-back shower, but you've reported doing at least two. Looking for feedback on your experience with this.
Thanks!
Every heat pump water heater on the market is a 'hybrid' design. They have resistance elements for backup. I agree there are niche applications where tankless heaters are more appropriate but in general any application where a traditional water heater is in use a heat pump can offer a replacement with no change in overall convenience. What bothers me is when tankless heaters are marketed as 'more efficient'.
If unlimited hot water is the goal then ideally you could put a tankless heater downstream of a heat pump heater... best of both worlds
It really depends on your application. A homeowner such as myself for example, that rarely uses hot water (take a shower, then I'm gone all day), would benefit greatly from a tankless (gas tankless for me).
Yes, please PM me, or post it, or perhaps even put it up on github?I'm happy to provide the script to anybody who is interested. Just PM me. If there is enough interest I can just post it here.
Most of your questions have been answered already, but yes, in Heat Pump mode, the electric elements generally stay off. They did kick on when I first fired up the heater, despite putting it in Heat Pump mode.I'm very interested in replacing our 12-year-old gas water heater with one of these HP Rheem units. Is it possible to force the resistive heat elements to stay off? Am I reading your graph correctly in that the unit draws less than 500W of power when heating? What is the amount of power draw should both resistive heating elements kick in? What is the breaker size required? The Rheem website claims only 1 back-to-back shower, but you've reported doing at least two. Looking for feedback on your experience with this.
The model I have has four options available. Pure Heat Pump , Hybrid, Electric Heater (conventional) and Vacation (for you northern folks that want to keep the tank from freezing but not use much power)I'm very interested in replacing our 12-year-old gas water heater with one of these HP Rheem units. Is it possible to force the resistive heat elements to stay off? Am I reading your graph correctly in that the unit draws less than 500W of power when heating? What is the amount of power draw should both resistive heating elements kick in? What is the breaker size required? The Rheem website claims only 1 back-to-back shower, but you've reported doing at least two. Looking for feedback on your experience with this.
Thanks!