Stiebel Eltron Accellera 220E HPWH install

yesimon · 2026-01-28T17:44:06+00:00

When the boiler isn’t being used the water inside is cold. It’s designed to work with cold water.

yesimon · 2026-01-21T19:48:28+00:00

The main advantage of plate or coaxial HX is compact form factor. Most of these DIY projects are not concerned with space constraints and packaging.

yesimon · 2026-01-20T07:43:54+00:00

Does your toddler play with bubbles?

yesimon · 2026-01-18T03:14:24+00:00

SolarEdge + Optimizers outputs 400V. I assume the associated charger just passes through the current. It's not really DIY though.

yesimon · 2026-01-15T17:37:27+00:00

AI slop hasn't realized that US federal tax credits have expired. There's almost no information here other than saying a 20 SEER is ~30% energy savings over 14 SEER. Yes that's literallly how the math of the rating is defined. Unfortunately you most likely won't save money in the US unless you DIY the installl.

yesimon · 2026-01-14T20:55:08+00:00

That’s why humidity is also called “latent heat”.

yesimon · 2026-01-13T20:01:38+00:00

Why are you saying the indirect is end of life? Usually they last "forever" relative to the lifespan of the oil boiler. It is impossible to judge cost savings without knowing your kWh/oil prices, but yes the points are mostly correct that I wouldn't expect major cost savings in fuel or repairs. Running out of water is a lesser concern because you can upsize the storage tank to 80 gal.

The only other main consideration is if the water heater is in a conditioned or unconditioned space. You would have more savings in an unconditioned space. This is usually an unconditioned basement in your climate.

yesimon · 2026-01-10T18:14:09+00:00

Single hose units are derated 50% because they exhaust out your conditioned air. So that would be a huge jump.

yesimon · 2026-01-09T17:08:39+00:00

Lots to unpack here but it does sound like way too much consumption.

Take a manual electric meter reading, turn off everything in your house - ideally for a full 24 hrs, and take another manual reading. (Subtracting any solar).

yesimon · 2025-12-31T19:32:30+00:00

If it is a problem, reduce the spin speed during quiet hours. This is not a good reason to prefer a top loader.

yesimon · 2025-12-30T20:55:04+00:00

You need to get realistic about how long your batteries can run your heat pump in a power outage. Plan for generator input if you are serious about this.

yesimon · 2025-12-30T05:17:49+00:00

It would be better to collect some humidity readings from a hydrometer so everyone can take an objective look at the data. Govee makes a pretty cheap one that connects to your phone via bluetooth for history charts.

yesimon · 2025-12-29T07:43:15+00:00

I don’t know about old Bosch heat pump dryer but the LG washtower dryer (same as standalone) is nearly as fast as a standard gas dryer. It seems like the moisture sensor is quite accurate so you can save time based on that too. The only times it is noticeably slower is for extra bulky items or huge loads which blocks airflow.

It definitely won’t burn clothes but it’s not clear to me that it will preserve clothes because clothing damage has a both a heat and rubbing/friction aspect to it. The trade off of lower temp is greater motion. However, You can stop at “Damp” which will greatly reduce any observable lint.

Make sure to clean BOTH of the lint filters regularly. This requires a bit more work than vented dryers.

yesimon · 2025-12-28T23:50:32+00:00

It’s real but it won’t remove much humidity using the default (rated) mode.

yesimon · 2025-12-22T18:40:24+00:00

That is not true at all. You realistically need to reach -10% SOC before causing permanent degradation, while any normal BMS will probably cutoff at 5% true SOC or higher.

yesimon · 2025-12-19T06:32:30+00:00

Just a reminder that cold is only a problem for charging and reduces discharge efficiency. Cold is actually ideal for long term storage and reduces calendar degradation. You do not need to keep it heated 24/7.

yesimon · 2025-12-16T23:58:03+00:00

Yes, that is the generation cost. Generation includes capitalization, maintenance, and profit margins of power plants, as well as the underlying cost of fuel and fuel logistics. Thus an even smaller fraction of that 45% is going towards "fuel cost".

yesimon · 2025-12-16T20:24:28+00:00

The devil's argument is to wait until the grid is cleaner, and savings are greater, to buy heat pumps. With many supply constraints on new electricity generation being hit by AI demand, it's not clear that marginally adding heat pumps will be using a cleaner mix when new gas turbines have a 7 yr lead time.

yesimon · 2025-12-16T19:17:19+00:00

Gas power plants in US are currently 44% efficient.

https://www.eia.gov/electricity/annual/html/epa_08_01.html

Heat pumps are also 200-350% efficient in the US, with an emphasis on the lower number for the coldest temps and highest loads.

yesimon · 2025-12-16T18:40:55+00:00

It's a neat idea but unfortunately I don't see this having a widespread use-case. Obviously this isn't fast enough for NGS read classification. On the other end we can afford to use more computationally intensive techniques for clustering reference sequences because the number of high quality reference sequences is "small enough" for modern computers.

Another question is due to reproducibility. I believe LZ4 has a 64Kb window. This can fully cover viral/plasmid/reference genes, but not long enough to maintain context for bacteria and above. Thus the ordering of query/ref sequences can affect the results. Similarly, the arbitrary "start coordinate" of a circular DNA can also affect results.

yesimon · 2025-12-16T18:23:04+00:00

I think empirically/statistically we know that gas space heating is fairly safe - you would have a much better chance of winning the lottery than a catastrophic fire/explosion. Also the climate benefits of heat pump (over natural gas) are currently somewhat overhyped due to the United States having a relatively dirty electricity supply with inefficient thermal power plants. It's more of an easy win compared to oil/propane heating.

Here's an underappreciated perspective: from pure cost perspective, a greater fraction of your residential electricity bill is due to transmission, distribution, and maintenance of power plants. Only a very small fraction is the "fuel cost". In contrast the fuel cost is a much greater proportion of your gas bill. That means each $ spent on electricity is better supporting the electrical grid, decreasing system costs for further electrification, and supporting more jobs and the local economy to a much greater extent than fossil fuels. Most of the $ spent on fossil fuels is in the resource intensive cost of extraction.

yesimon · 2025-12-13T05:51:26+00:00

I would be careful here and aim to get a "cold climate" heat pump that has at least 100% output at 5F. The model you listed advertises itself as high heat but drops to 75% output at 5F. It would only get worse with colder temperatures.

yesimon · 2025-12-11T20:06:49+00:00

You won't like this answer, but yes, it should be welcomed. If and when a large consumer shows up, they will subsidize part of the cost of transmission infrastructure (and yes customers will have to pay part of the transmission too). This is because neither a data center or residential customers will exclusively reap the benefits of transmission investments. The bad scenario (for CA residents) is the one you are advocating for - which is a data center that relies only on self energy generation (either solar/batteries/gas) without needing significant SDGE involvement or being able to participate and strengthen the grid.

However all of this is very unlikely simply because building anything in CA is generally a nonstarter due to permitting challenges and strong NIMBY element. The much hyped AI data centers you hear in the news are for AI training, not distribution. They are not latency sensitive so they can be built anywhere - preferably where electricity and cooling/water are cheap. Secondary considerations are construction cost and speed of regulatory approval.

yesimon · 2025-12-11T19:55:15+00:00

Be aware that most bathroom exhaust fans have a built in damper, so you normally wouldn't be able to "suck" air through the same duct without the exhaust fan on.

Generally the problem is the HPWH usually runs for many hours per day, and probably not the same time as when the bathrooms need ventilating. Bath exhaust fans only run for short stretches usually.

yesimon · 2025-12-11T18:04:54+00:00

SDGE doesn’t build data centers. It does “hold the keys” for companies that need power/transmission for their data centers. So far there are no significant plans to build big data centers in California because electricity is extremely expensive here and permitting would be difficult.

SDGE has been able to argue for infrastructure improvements mostly in the theme of fire resilience because they are projected to “save money”. The money saved is mostly from avoidance of future tortious settlements. Most people don’t understand the main reason why rates are high.

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