The Home Improvement Thread. Successes and Failures

[walrus]

Was thinking about this too. My house used to be insanely energy efficient, even without the massive tree growth I've had over the last decade. 100 degree day, the temp never got about like 76. Now, not so much. Which is why I'd like to look at a couple things. Energy audit (walls, ceilings, and attic), add insulation to the attic. I'll also be looking to replace the hot water heater, but not sure that's going to save much.

Not sure what else I can do.

If the water was hot, you wouldn't need a heater Energy audit is a good thing. Minnesota may have incentives for insulation. Maine does. Depends on how you heat your water whether or not you can save any money. Heat pump hot water heaters work well but don't recover quickly.

 

[dxmnkd316]

If the water was hot, you wouldn't need a heater Energy audit is a good thing. Minnesota may have incentives for insulation. Maine does. Depends on how you heat your water whether or not you can save any money. Heat pump hot water heaters work well but don't recover quickly.

The water heater is >11 years and I'm not super keen on risking it. Plus, it's starting to not hold heat that well. I'm not entirely sure why. We usually have to run the dishwasher overnight or you basically get a lukewarm shower. I don't want to turn up the heat any more either. It's gas fired. Was starting to look at ground source heat pump incentives, but I think that's asking for problems in the clay heavy area I live in. Air source heat pumps are interesting but I'm not sure this is the right application for a number of reasons (house layout, etc)

I'm guessing the temp sensor is fouled pretty bad. We have hard water but I flush it every year. Usually don't get much out but some super fine sediment. It's supposedly a self-cleaning heater but not sure how that works or if it's just a marketing gimmick. The fact that I usually don't get much out is probably a good thing. Otherwise I'm not sure what would cause it to reheat.

Was planning on getting a water softener too at the same time since it would save a couple bucks overall on install and let us plan for both more efficiently in terms of layout. Was also looking at tankless, but the horror stories on those, even if uncommon, are truly horrible. And the payback is still utter garbage.

 

[LynahFan]

And the payback is still utter garbage.

No doubt. Any discussion of payback is pure marketing greenwashing. You might be able to squint and pencil whip some savings on a equivalent volume basis, but the whole point of the tankless heater is that you ca. take a 3-hour shower and not run out of hot water. That ain’t saving anyone any money!

 

[SJHovey]

No doubt. Any discussion of payback is pure marketing greenwashing. You might be able to squint and pencil whip some savings on a equivalent volume basis, but the whole point of the tankless heater is that you ca. take a 3-hour shower and not run out of hot water. That ain’t saving anyone any money!

As someone who was living in a household with a wife and three teenage daughters when I installed our tankless water heater, I can only describe it as a miracle of modern engineering, and a godsend.

 

[BassAle]

No doubt. Any discussion of payback is pure marketing greenwashing. You might be able to squint and pencil whip some savings on a equivalent volume basis, but the whole point of the tankless heater is that you ca. take a 3-hour shower and not run out of hot water. That ain’t saving anyone any money!

but you're only paying to heat the water once with a tankless. With a tank, you're paying to bring the water up to temperature and then paying to maintain it at that temperature until someone uses it

 

[BassAle]

I love my Nest. Keep house around 65 all winter. That and adding insulation has been key

my wife would murder me in my sleep if I tried to keep the house at 65.

 

[dxmnkd316]

my wife would murder me in my sleep if I tried to keep the house at 65.

My wife wasn't thrilled either until she started sleeping better with a cold room and warm blankets. We more or less sleep nordic style where she has a couple extra blankets under the main comforter, at least in the winter. I sleep warm and basically get zero sleep if the room is at 70+.


We did compromise up from my original of like 63-64. It would have killed her orchids since our thermostat is placed in the hallway which is in the dead center of the house across from the bathroom where there's a vent point towards it. Which very roughly looks like this (the bathroom on the main level is shared between master and hallway). Anyways, the thermostat is stupid because it heats up before everything else does. One more reason we're getting the Ecobee which has multiroom controls.

 

[LynahFan]

but you're only paying to heat the water once with a tankless. With a tank, you're paying to bring the water up to temperature and then paying to maintain it at that temperature until someone uses it

Uh, oh. Now you done it - made me go and do some calculations.

Say you take a 10 minute shower at 2.5 GPM (typical) of 120F water, and your water supply comes into your house at 70 F. The energy used to heat those 25 gallons of water by 70F is 10,000 BTU.

Now, if your hot water heater is 6 ft tall and 2 ft in diameter and has an insulation R-value of 24, then the rate of heat loss (to your 70F house) would be (6 * 2* pi) * 50 / 24 = 78 BTU/hr. So for your hot water heater to lose as much heat as you use in a single, 10 minute shower would take 127 hours - more than 5 days.

That right there should convince you that your hot water energy bill is driven by usage and not maintaining the temperature of the hot water heater. But in case you're still not convinced:

On a weekly basis, if you take a 10 min shower every day, you'd be paying for 70,000 BTUs to heat water "initially" and for 78*168 = 18470 BTU to maintain it, for a total of 116K.

Now, you can eliminate the 18470 maintenance BTUs by going tankless, but if that tankless water heater tempts you to add just 2 minutes to each shower, then you won't reduce - you'll break even.

If you have a wife and 3 teenage daughters, so that your nominal weekly usage is 7*5*10 = 350 minutes of showering, then your break-even is at a whopping 10 min 22 seconds per shower.

 

[walrus]

As someone who was living in a household with a wife and three teenage daughters when I installed our tankless water heater, I can only describe it as a miracle of modern engineering, and a godsend.

Tankless water heater and teenagers, screw that, they will be in the shower forever.

 

[dxmnkd316]

This thread is amazing

 

[SJHovey]

If you have a wife and 3 teenage daughters, so that your nominal weekly usage is 7*5*10 = 350 minutes of showering, then your break-even is at a whopping 10 min 22 seconds per shower.

You are obviously excellent at math, but maybe not so much at teenage girl math.

Teenage girls are like mice. If you see three of them in your home, you almost certainly have many more running around somewhere in the building.

Second, the volume of laundry and dishwashing in such a household defies normal expectations.

Third, ten minutes is nothing when there are fourteen separate beauty and hair treatments that have to be undertaken.

 

[Kepler]

Tankless water heater and teenagers, screw that, they will be in the shower forever.

Can confirm.

I'd say "what are they doing in there?" but I was a teenager.

 

[Kepler]

My wife wasn't thrilled either until she started sleeping better with a cold room and warm blankets. We more or less sleep nordic style where she has a couple extra blankets under the main comforter, at least in the winter. I sleep warm and basically get zero sleep if the room is at 70+.

This is The Way.

I also have a sleeping body temperature of about 170 degrees, so that helps.

 

[walrus]

I have a small passive solar house, this time of year if sun is out its easy to get house in the 70s. In the dead of winter I heat with wood. One centrally located wood stove heats the house easily and temp in living room is generally low 70s. I just installed a ground mount Solar array, 8600 watts. My goal is utilize 2- 12k ductless mini splits to lower the amount of wood I burn and to make it easier to control temps in the shoulder seasons, fall and spring. We shall see if it works. So far I have been impressed with the output of the solar.

 

[Swansong]

Uh, oh. Now you done it - made me go and do some calculations.

Say you take a 10 minute shower at 2.5 GPM (typical) of 120F water, and your water supply comes into your house at 70 F. The energy used to heat those 25 gallons of water by 70F is 10,000 BTU.

Now, if your hot water heater is 6 ft tall and 2 ft in diameter and has an insulation R-value of 24, then the rate of heat loss (to your 70F house) would be (6 * 2* pi) * 50 / 24 = 78 BTU/hr. So for your hot water heater to lose as much heat as you use in a single, 10 minute shower would take 127 hours - more than 5 days.

That right there should convince you that your hot water energy bill is driven by usage and not maintaining the temperature of the hot water heater. But in case you're still not convinced:

On a weekly basis, if you take a 10 min shower every day, you'd be paying for 70,000 BTUs to heat water "initially" and for 78*168 = 18470 BTU to maintain it, for a total of 116K.

Now, you can eliminate the 18470 maintenance BTUs by going tankless, but if that tankless water heater tempts you to add just 2 minutes to each shower, then you won't reduce - you'll break even.

If you have a wife and 3 teenage daughters, so that your nominal weekly usage is 7*5*10 = 350 minutes of showering, then your break-even is at a whopping 10 min 22 seconds per shower.

I know better than to question your math, but there is a lot more than just shower use in terms of hot water.



I did not go with a tankless system when I needed to replace my heater last year, but it was more about the fact that the installation would have been crazy expensive for me as they'd have had to re-plumb my entire system. Right now my boiler and hot water heater are next to each other in the middle of the basement, next to the central chimney. Tankless systems must be installed on an external wall and vented, so I'd have had to run gas lines, all the plumbing and power to a part of the wall that doesn't have those things, plus I'd have to cut a hole in the wall for said vent.


Also, my hot water heater and boiler both went on the same day, so I was already facing a $NASA installation/equipment charge.

 

[LynahFan]

I know better than to question your math, but there is a lot more than just shower use in terms of hot water.



I did not go with a tankless system when I needed to replace my heater last year, but it was more about the fact that the installation would have been crazy expensive for me as they'd have had to re-plumb my entire system. Right now my boiler and hot water heater are next to each other in the middle of the basement, next to the central chimney. Tankless systems must be installed on an external wall and vented, so I'd have had to run gas lines, all the plumbing and power to a part of the wall that doesn't have those things, plus I'd have to cut a hole in the wall for said vent.


Also, my hot water heater and boiler both went on the same day, so I was already facing a $NASA installation/equipment charge.

Exactly - and that's why they never pay. NA$A to install, and the "maintenance heat" that you save compared to all that usage (which I meant to point out that I was being very, very conservative on, especially in the teenage girl department) is vanishingly small.

If you want the luxury of unlimited hot water - pay NA$A and own it as a luxury item. Don't buy one thinking that you're cleverly beating the system and somehow saving money.

Edit to add: we're about to install one.

 

[dxmnkd316]

Edit to add: we're about to install one.

Gut laugh.

 

[walrus]

Plus tankless heaters are expensive to service.

 

[dxmnkd316]

One thing I saw that probably cuts water usage by at least double digits from Gen 1 TWHs was the recirc loop. TWHs take a bit to get up to temp, so you're basically just dumping water down the drain. Some come with a recirc loop (not sure how this works with regards to opening a tap and waiting) that gets the water up to temp and then sends it to the hot water header. Again, it's just one more pain in the ass thing to break and... Jeeze, I dunno man. I'd rather just buy a 12" thick bat of insulation than worry about 100 parts failing.

Too bad we can't just make these things out of hastelloy, make them vacuum insulated pressure vessels, and they'd outlast the cockroaches.

 

[dxmnkd316]

Plus tankless heaters are expensive to service.

Yeah, the nightmare stories I've seen where "Oh, part XYZ failed and you can't really service it so they make you send in your unit to prove it defective and they'll send you a new one". Given the supply chain issues now, I'm opting for simplicity. Or efficient and complicated with a simple backup (like keeping my non-smart thermostat in case the ecobee takes a dump).