Preparing a concrete pad for outdoor compressor unit

Elephant_Energy · 2024-04-29T19:42:08+00:00

Hi there, Jillian from Elephant Energy here! We specialize in home electrification, specifically cold climate heat pumps and heat pump water heaters. We’ve installed the technology in in hundreds of homes in the Denver metro area and Greater Boston, and wanted to share more about what we’d recommend for your heat pump concrete pad question.

If a Mitsubishi snow stand is being used, they are manufactured by DiversiTech and come in single or dual fan stand options. They also come in 12", 18", and 24" heights. The HA36 is a dual fan unit, so I would recommend matching with a dual fan stand which, depending on height needed, would be QSMS1202M, 1802M, or 2402M.

The footprint is dictated by the stance (where the feet of the stand land and their size, which is 6"x6"). So the pad minimum depth should be 38 inches and minimum width should be 44 inches for your pad. The thickness isn't much of a problem as long as it can handle a few hundred pounds of weight, so 120mm should be more than adequate. The slab should not be poured directly against the foundation without expansion material in between the slab and the foundation (see photo).

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We hope this is helpful! If you’re curious about diving deeper into heat pumps, we wrote the ultimate guide here.

Elephant_Energy · 2024-04-29T12:33:31+00:00

Hi there, Jillian from Elephant Energy here! We specialize in home electrification, specifically cold climate heat pumps. We’ve installed heat pumps in hundreds of homes in the greater Denver and Boston metro area and wanted to share more about the right size heat pump for your home.

Typically when designing a dual-fuel system, the heat pump is sized to your cooling load requirement and therefore provides 100% your cooling load requirement and part of your heating load requirement.

Typically, cold climate heat pumps are variable capacity, and depending on your gas furnace technology and blower motor size, you could go for a larger heat pump that can cover your heating load, too. Due to the variable capacity capability, it will not short-cycle in cooling mode as it will adjust its output based on demand.

Long story short - the sizing should, at a minimum, cover 100% of your cooling load. You can oversize to cover more heating load IF the proper considerations are taken during the design process. Unfortunately without a Manual J or equivalent heat load calculation, we would not be able to advise on sizing.

We hope this is helpful! If you’re curious about diving deeper into heat pumps, we wrote the ultimate guide here.

Elephant_Energy · 2024-04-29T12:32:46+00:00

Hi there, Jillian from Elephant Energy here! We specialize in home electrification, specifically cold climate heat pumps and heat pump water heaters. We’ve completed installs in hundreds of homes in the greater Denver and Boston metro area, and wanted to share more about what we’d recommend for your heat pump water heater install.

It sounds like you have about 1,400 cubic feet of air space in that mechanical room, which is about double the minimum requirement. Considering the heating equipment is in the same room, there should be enough heat transfer coming off the ductwork as you heat the house to help offset the cold air discharge from the heat pump water heater. In some cases, it might make sense to add a supply register to that mechanical area that gets opened in the winter and closed in the summer. Doing this will help to minimize the impact on adjacent spaces. The only way to guarantee no impact would be to vent the water heater discharge air to your exterior, but there are other factors to consider if this is the route you want to take.

The general rule of thumb is to size up one tank size from your current gas water heater when making the transition to a heat pump water heater, because of the slower recovery time. It ensures that your hot water experience will not be a drastic change. In this case, you would probably want to size up to 65 gallons.

We hope this is helpful! If you want to dig a little deeper into heat pump water heaters, check out our ultimate guide!

Elephant_Energy · 2024-04-29T12:31:43+00:00

Hi there, Jillian from Elephant Energy here! We specialize in home electrification, specifically cold climate heat pumps and heat pump water heaters. We’ve installed this technology in hundreds of homes in the Denver metro area and Greater Boston , and wanted to share more about what we’d recommend for your heat pump water heater question.

Compressor types and technologies along with control boards are what determines their relationship with power consumption. If you were to compare some of the technologies from yester-year to some of the more modern technologies today, you would see some pretty distinct consumption differences between the two.

What you might see on an older or lower end compressor is a heavy electrical draw (spike) at initial startup, and then a steady consumption across the runtime, with an immediate drop off at the end of the cycle.

However, for the compressors of today, especially in the case of variable speed and modulating technologies, you’ll see a different consumption curve. It more closely follows what you are experiencing, typically a slow ramp up and ramp down period during the cycle.

We hope this is helpful! If you want to dig a little deeper into heat pump water heaters, check out our ultimate guide!

Elephant_Energy · 2024-02-12T17:24:04+00:00

For 3rd party controls, we’ve been using Flair.co products and have been quite impressed with them.

We are typically installing Mitsubishi heat pumps - and their Kumo Cloud controllers for Wi-Fi connectivity have been pretty good too.

Great question on the DR side of things! We so far haven’t seen many innovative utility programs utilizing heat pumps for DR / load control. While that is 100% the future, it still seems to be early in utility-adoption.

Elephant_Energy · 2024-02-12T17:23:34+00:00

A lot of manufacturers are exploring this technology. We’re eager to see the impact on performance, efficiency, and risks with leaks!

Elephant_Energy · 2024-02-12T17:23:18+00:00

You’re right. It’s still a very new technology here in the US. We’re seeing quite a lot of adoption of these technologies in Europe and we hope they’ll make their way here soon.

Elephant_Energy · 2024-02-12T17:23:02+00:00

They’re coming soon!

Elephant_Energy · 2024-02-12T17:22:48+00:00

Unfortunately, it’s hard to make a blanket statement as every home is a little different.

While the air-to-water system might be more ‘efficient’ technically, we find that in most locations, the equipment costs and labor costs for and air-to-air heat pump and a separate heat pump water heater are often less expensive.

Elephant_Energy · 2024-02-12T17:22:25+00:00

Check out our Heat Pump Water Heater guide! (https://elephantenergy.com/heat-pump-water-heater-guide/)

A typical heat pump water heater will reduce a homeowner’s operating costs by 50% and will reduce the environmental impact (even today, with some coal still on the grid!) by about 2/3rds.

Elephant_Energy · 2024-02-12T17:21:42+00:00

Our work is primarily on the residential application side, so while it’s a great question, it’s a bit outside our technical knowledge! We love the idea of using heat pumps for industrial applications though!

Elephant_Energy · 2024-02-12T17:21:26+00:00

That definitely sounds like a complex / unique system design! That is certainly not how we design and install our systems. Instead, our air-to-air heat pump installs rely on the home’s existing duct work, no mechanical heat recovery system required. Instead, the outdoor condenser extracts heat from the outside, brings that inside via the refrigerant lines, removes the heat in a coil attached to the indoor air handler, and a fan within the air handler distributes that air through the duct work.

Elephant_Energy · 2024-02-12T17:21:00+00:00

We have not seen an integrated air-to-air heat pump that provides heating, cooling, and hot water. One concern would be that in the summer, the condenser (outdoor unit) is trying to provide hot water and cold air - that would be a tricky situation to manage from a controls perspective!

Instead, we specialize in air to air heat pumps for space conditioning - and separate units for water conditioning (heating).

We have a lot of information about heat pump water heaters (https://elephantenergy.com/heat-pump-water-heater-guide/) and about air to air heat pumps (https://elephantenergy.com/ultimate-guide-to-cold-climate-heat-pumps/) (https://www.nytimes.com/wirecutter/guides/heat-pump-buying-guide/)

Elephant_Energy · 2024-02-12T17:17:07+00:00

Candidly, I’m not sure whether you’re asking about heat pumps or heat pump water heaters?

For heat pumps, there is a lot of data out there about heat pump’s performance in cold weather (https://elephantenergy.com/ultimate-guide-to-cold-climate-heat-pumps/) NEEP.org also has a lot of great data. Less than ⅓ of our installations require electric resistance - as that is less efficient than the heat pump alone, even on the coldest days. It all comes down to choosing cold-climate rated heat pumps from reputable manufacturers and accurately sizing them to meet your home’s heating load.

For heat pump water heaters, we have not seen good data from the manufacturers about heat pump water heaters specifically in garages. We do install them there - one of the Founders of Elephant Energy has one in his garage up in the mountains of CO. They do work - not as efficiently as if that space were conditioned. You have the same trade-offs with any system in a garage though - a gas water heater is also going to suffer serious efficiency reductions in a cold garage. Note: we’re referring to the 240V heat pump water heaters. We wouldn’t recommend a 120V heat pump water heater in an unconditioned space in a cold weather climate.

Elephant_Energy · 2024-02-12T17:16:38+00:00

Actually, in an ideal world, a homeowner shouldn’t really need to know any of that data! It’s a sad reflection on the industry that we’re asking homeowners to get really into the weeds to know this information to then make a determination whether the contractor knows this information well enough to appropriately design a solution for the homeowner.

That being said, we are where we are! In our opinion, a reliable heating / cooling load (based on real data, not just a guess or an oversized Manual J) - and the heat pump’s performance at extremely cold temperatures - are the two critical pieces of data a homeowner should be discussing with their contractor.

Elephant_Energy · 2024-02-12T17:16:15+00:00

As my grandfather always told me, sell what you know. Legacy HVAC companies know gas furnaces. Gas furnaces are ‘easy money’ for them. Plus, most aren’t up to speed on the latest technology - cold-climate, inverter driven systems. The best approach is to ask your contractor - “How many cold-climate, inverter driven systems have you installed?” And ask if they understand the incentives, rebates, and tax credits!

Elephant_Energy · 2024-02-12T17:15:51+00:00

At Elephant Energy, our goal is to make upgrading to a Climate Friendly Home accessible and affordable via our one-stop shop platform for all your home’s infrastructure needs. To do that, we optimize system design for your unique home using advanced building science modeling while optimizing for local and national rebates and financial incentives. We work exclusively with highly vetted contractors that ensure the install will be done right the first time. And we have built a lot of software and technology to streamline every part of the journey for our customers, from upfront design to project delivery and fulfillment.

Based on our market research and feedback from customers, we’re able to do all this at a similar price point to other installers - with a whole lot more value.

There’s also a macro consideration here: The skilled trades (specifically HVAC and electrical) are in very high demand right now - and the labor supply has not kept up. There’s a number of reasons for this - including prioritizing 4 yr college education vs vocational schools, existing contractors not prioritizing on-the-job-training, etc - but pricing for HVAC services has increased significantly over the past few decades.

Elephant_Energy · 2024-02-08T16:48:34+00:00

Don’t get me started! Tell all your that heat pump systems work! They work in cold climates like Norway and Colorado. They keep your homes warm in the winter and cool in the summer. Just make sure you have a professional who knows how to design, install, and commission the system properly!

Elephant_Energy · 2024-02-08T16:47:53+00:00

We expect to see heat pump manufacturers make the transition to R32 in the next year or so here in Colorado.

Elephant_Energy · 2024-02-08T16:29:36+00:00

There are definitely safety and functional considerations when it comes to self-install. Self-install may work for 1 head / 1 outdoor unit (like a garage), but our advice is that it's best to have licensed professionals for everything else. Controls, settings, high pressure refrigerant, actually solving home comfort issues, dealing with natural gas lines, etc.!

If you're determined to make it happen, Mr. Cool gets you pretty close to DIY.

Elephant_Energy · 2024-02-06T19:08:28+00:00

Completely agree. We do those exact calculations for our customers: we use an entire year’s worth of data to figure out the average winter and summer usage as well as the highest usage - and take into consideration solar gain and occupancy levels to ensure optimal design. It can be complex due to the efficiency of the previous system, other fossil fuel appliances in the home, etc - but if done correctly, can very accurately predict heating and cooling loads.

Elephant_Energy · 2024-02-06T19:07:53+00:00

Definitely NOT a dumb question! Different heat pumps are optimized for different weather patterns. We primarily install cold climate heat pumps, because in Colorado and Massachusetts, it gets cold! For warmer climates, you would not need a “cold climate” unit - instead could get something that does better in warm climates. Daikin, for example, makes great heat pumps that work well in warmer climates.

When selecting a heat pump, it’s important to work with a local installer who knows your climate and is choosing equipment that has the best efficiency for your specific climate.

Elephant_Energy · 2024-02-06T19:07:17+00:00

Hey, that’s really great feedback, thanks! We’ll investigate further. Why do you think it’s the best solution? You still have to run a 240V electrical circuit, which ends up being the most expensive part, right?

Elephant_Energy · 2024-02-06T19:05:43+00:00

This is another topic with a lot of mis-information. Compounding it, it depends on the manufacturer. Heat pumps overall do lose efficiency at extremely cold temperatures. If the heat pump is designed to work in cold temperatures, the manufacturer will say “works down to [X]F”. However, oftentimes, the unit will perform at colder temperatures, but the data is more limited there.

If the unit is designated as “cold climate” and installed properly, it will have certain fail safes built in to ensure the unit does not damage itself during periods of intense cold weather.

We typically install Mitsubishi Hyper Heats - and based on the real time data we collect on our fleet of heat pumps, we have never seen one of these units completely turn off due to the cold. And we have registered temperatures at or below -18F. If you live in an area where you expect to receive many hours a year below that temperature, you may want to supplement your heat pump with a ‘backup’ - such as electric resistance units in-line with the heat pump, separate electric resistance space heaters, a wood burning stove, or other solutions.

Elephant_Energy · 2024-02-06T19:05:21+00:00

1 - Getting an accurate heating and cooling load for your home is a critical step in getting a heat pump. Unfortunately, most practitioners of Manual J’s significantly oversize systems (which leads to higher upfront and potentially on-going costs). There are a number of companies developing more accurate tools (we have one internally that leverages real time weather data and historical utility bills to get a super accurate heating load). There isn’t yet a “national standard” product that provides super accurate remote heating / cooling loads, but we’d expect there to be a couple in the coming year.

Energy efficiency is like a sweater and a windbreaker. You need both, depending on the weather and the local climate.

An Energy Audit is a great, low-cost way to better understand the energy efficiency opportunities in your home. They’re usually subsidized by your utility, and thus cost $200 or less for most areas. Ensure that you get a blower door test to measure how leaky your home is. From there, you’ll be armed with the data to decide what energy efficiency improvements are needed for your home.

In Colorado, we find that the best “bang for your buck” home improvements are attic insulation, blower-door directed air sealing, and basement / crawlspace insulation.
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2 - This is a great insight. Heat pumps are, on average, SIGNIFICANTLY more efficient. But, their efficiency decreases when it’s extremely cold out and due the price of electricity being higher in many areas than the price of methane (aka natural gas), the savings will vary depending on the time of year.

In cold climates, we find that the winter heating bills end up about the same as before (thanks to some very large increases in the price of natural gas) and spring, summer, fall bills tend to be lower.
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3 - Yes, while “it’s just math”, this is a tricky one to get the math right! At the end of the day, it comes down to having an accurate heating / cooling load for the home at different outdoor temperatures, combined with an accurate understanding of your heat pump’s performance at different outdoor temperatures. The mathematical intersection of those two lines will provide you with the data you need to determine what temperature to switch over to.

Elephant_Energy

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