Can I trenchdig a small area to drop my crawl space floor by 6 inches for a heat pump water heater installation to reduce energy fees?
Asked by Barb Day 
2 months ago
Last Updated: October 29, 2024
Hey there! I’m thinking about replacing my water heater since it’s pretty energy-intensive (just look at the chart showing how much we use during shower time). I’m considering a heat pump water heater to help cut down on energy costs, even though I know they can have some drawbacks like producing cold air. I don’t think that will be a big issue in my climate, though. The only thing is, my water heater is in a tight space in my crawl space. Do you think it’s possible to dig a small trench to lower the floor by about 6 inches? I’ve seen some photos of others doing it, but I’d love to get some advice from a group of knowledgeable folks like you.
There’s no such thing as free energy. Heat pumps run on electricity!! No savings here. Have you thought about why your current fuel source is so expensive? Are all the hot pipes properly insulated? If so, with what material? How efficient is your system? Have you considered a thermosyphoning loop? Have you looked into a HWR – hot water recirculation system?
Installing a recirculator will only cause your water heater to consume more energy, as it keeps the entire recirculated line warm.
Not sure why you would think I am looking for “free energy”. Heat pump water heaters are significantly more efficient than even brand new electric water heaters.
Maybe I’m missing something, but how would insulating the hot pipes help? The large spikes in energy use only occur when using large amounts of hot water. Maintaining that temperature seems to be quite minimal based on the rest of the day’s usage.
Aren’t HWRs used to prevent delays in hot water at faucets and showers? I don’t really encounter that issue. Even the longest run gets hot water within about 20 seconds.
No
Sorry you don’t understand how it works and why they will be included in residential building codes by 2025.
When installed correctly, both thermosyphons save significant amounts of water. The poster even admits that they take 20 seconds to get hot water. That’s a considerable amount of water and energy to use and pay for. All while being mindful of their usage 😊 !
OP doesn’t mention how they measure “efficiency”, so any changes made have no way of being monitored. It has nothing to do with costs – that’s completely unrelated to efficiency.
Simply purchasing new is a very poor response to perceived low efficiency. We covered this in detail back in 1993-9 with National Energy Auditors. That was 31 years ago.
It’s just absurd now in 2024 to even consider this.
How long are your showers? 5-7 minutes is quite a long time.
Do you have flow restrictions / aerators on all shower heads and faucets? They are not included with the fixtures.
OP wonders what insulation has to do with hot water consumption!! This is taught in grade 5 science here in 🇨🇦.
Sometimes you just have to go to a library and read a few books.
Haha.
I didn’t mean to sound demeaning, so I apologize if it came across that way. In the US, residential codes do not mandate recirculating lines, but they are required commercially for legionnaires disease prevention. I am curious how you think a recirculation line improves efficiency, could you explain further? In an extreme scenario, a hot water loop holding 10 gallons means you are constantly heating and maintaining 50 gallons instead of the designed 40 gallons. Additionally, a water heater like the Bradford White RE240T6 with 2″ of R-16 insulation will retain heat much longer than one with a recirculation pump and likely uninsulated piping.
Regarding the idea of digging a trench for a larger water heater, I would advise against it as it essentially creates a sump pit for the water heater. Newer water heaters are much more efficient due to various factors. Since yours is electric, check the ratings of newer electric water heaters compared to your current one. New water heaters are nearly twice as efficient in terms of first hour efficiency.
Yeah, I understand that with the sump pit. I am aware that the newer water heaters are more efficient than the older models. Unfortunately, to get one of those with rebates from my electric company and federal assistance, they would cost the same as a heat pump unit. I thought if I could achieve efficiency savings with the same initial costs, I might as well do that. Thanks for the information.
O for the heat pump unit. Consider digging if necessary. Use a lining if water infiltration is a concern. Also, opt for a slightly larger heat pump unit for better efficiency and cost savings. Upgrading to a bigger unit resulted in immediate electricity savings for me when I installed mine 8 months ago.
Thank you! The digging aspect is my main concern. I frequent the crawl space often and was thinking of lining the hole with thick poly and placing a pan underneath.
If you shower in the evenings, a cost-effective way to reduce hot water expenses is by installing a black water tank outside that feeds your water heater with preheated water. This is a common practice worldwide but not as much in the US.
Lenny emar thanks! It’s not very common in the US yet. We’re quite fortunate here. I’d love to do something like that if my house faced south, but finding a discreet location for the tank might be a challenge. The HOA might not approve. 🙂
Are you allowed to have solar panels on your roof? You could consider installing water solar panels that connect to a storage tank inside your home or in the backyard. A recirculating pump would cycle the water through the panels during the day, storing hot water in the tank for your use. It may cost more than a conventional setup, but it could be worth it in the long run. Back in the day, we had a similar system for heating our pool.
Lenny emar yeah, I have come across those. It’s a fantastic idea, but if I am going through the effort of installing solar panels on my roof, I plan to install a substantial amount and use it for my entire house.