Hot Water Lobster - Page 3

ryanwc · 02-13-15, 12:08 AM

Anyway, I just tested my hot water from the upstairs bathroom sink. 18 dumps of my 16 oz. cup got me to warm though not yet hot. To get actual hot water is surely 3 gallons per time.

The pipe coming from the heater is always somewhat warm in the first few feet just from heat circulating up out of the heater itself, and I had thought it was uninsulatable because standard foam isn't recommended so close to high temperatures.

I can't help but think if I could insulate it there, the insulation around the pipe running the rest of the way through the basement would stay warm, perhaps cutting in half the amount of water that had to be drained before I got warm or even hot water for my shower upstairs.

I'm now realizing that fiberglass pipe insulation may be appropriate in this setting. Anyone have any experience, thoughts or concerns about fiberglass pipe insulation right next to the hot water heater smokestack?

Xringer · 02-13-15, 09:54 AM

I've used sheet metal heat shields while working on copper with a propane torch.
It blocks the heat and keeps from setting wood on fire.

Installing a Heat Shield between single wall vent pipe and combustible material - YouTube

If you have a good amount of space between the stack and the hotwater pipe,
you might be able to insulate the hw pipe with regular foam insulation,
wrap it up with foil tape to make it reflect heat,
then suspend a steel heat shield between the hot stack and the water pipe..

FYI, in case you don't know, a good heat shield will be very shiny..
Shop IMPERIAL 24-in x 36-in GV Flat Sheet at Lowes.com

This one, could be shaped into a parabola, with the bends towards the stack.
It should not be in contact anything that will burn..

~~~~
You could also just buy some PEX and re-route the hotwater away from the stack.. Might be faster and cost about the same..

ryanwc · 02-13-15, 04:26 PM

I went ahead and wrapped it with unfaced fiberglass, covered by foil tape. Though the EPA and others offer the bizarre advice to use unfaced fiberglass within 8 inches of the flue, but not to insulate within 6 inches of the flue, other sites that seem knowledgeable say you can use unfaced fiberglass closer; and the Home Depot plumbling guy felt it would be fine. The pipe runs parallel probably 3.5 inches from the flue. It's closer where the flue flanges outward as draftguard/indoor air intake, but that flange shouldn't get very hot, since it has indoor air flowing past it.

Xringer · 02-13-15, 05:43 PM

Fiberglass can burn/breakdown, if you hit with an open flame. But, this says 450F is okay..
Fire Safety Insulation Performance and Testing - About Insulation : NAIMA North American Insulation Manufacturers Association

The Big Burn - YouTube

If you can measure the heat that's hitting the foil, and it's under 450F, you might be good to go..
The no-contact heat scanners are what I use to measure surfaces.

mechanic · 02-13-15, 07:25 PM

When my house was built there was a pump and recirc line put in for the main and onsuite bathrooms as they are opposite side of the house as the utility room (~50'). It had a timer which was poor as my wife works shift work and I'm a day worker. It cost a fortune to run all the time as our water heater is electric and would run often, and with the pump off you would run the shower for five minutes before you got in and it would still be on full hot when you got out having never gotten that warm with all the heat loss and I suspect some backwards flow from the pumps return line on the cold feed side of the water heater... I ended up buying a bunch of cheap pipe insulation from Home Depot and insulated all the lines then I put a timed switch on the wall for the pump, just hit the button 30 seconds before you turn the shower on and it's instant hot then just turns itself off so nobody forgets it, works great!

mechanic · 02-13-15, 07:27 PM

Oh and I also put a heat exchanger in the shower drains that acts on the incoming cold water to the showers, you gotta keep turning the hot water in the shower down as you go��

ryanwc · 02-13-15, 10:56 PM

The result of using about $1 of unfaced fiberglass wound around roughly 14" of pipe at the connection to the water heater, and then wrapping that in foil tape leftover from another project, was that the water was warm after about 270 oz. down the drain, vs. 318 oz. last night prior to the mini-project. (The pipe was already insulated with foam for another 20 feet, but with that 1-foot gap at the heater, the down-time heat that leaks up out of the heater was simply being lost, and the rest of the pipe would cool fairly quickly once a use was over.)

It'll have a bigger percentage impact on the kitchen sink, which is closer to the water heater, and may also have a bigger impact in uses that come within 15 minutes of each other, since the pipe should stay warmer longer.

It'll have more of an impact on my time than my budget by letting me step in the shower sooner, wash a dish sooner, etc. But it'll also pay for itself.

Thanks, xringer, for the word of caution. I'll keep an eye on it, but I don't think it could get that hot.

02-13-15, 09:54 AM	#22
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I've used sheet metal heat shields while working on copper with a propane torch. It blocks the heat and keeps from setting wood on fire. Installing a Heat Shield between single wall vent pipe and combustible material - YouTube If you have a good amount of space between the stack and the hotwater pipe, you might be able to insulate the hw pipe with regular foam insulation, wrap it up with foil tape to make it reflect heat, then suspend a steel heat shield between the hot stack and the water pipe.. FYI, in case you don't know, a good heat shield will be very shiny.. Shop IMPERIAL 24-in x 36-in GV Flat Sheet at Lowes.com This one, could be shaped into a parabola, with the bends towards the stack. It should not be in contact anything that will burn.. ~~~~ You could also just buy some PEX and re-route the hotwater away from the stack.. Might be faster and cost about the same.. __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

02-13-15, 05:43 PM	#24
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Fiberglass can burn/breakdown, if you hit with an open flame. But, this says 450F is okay.. Fire Safety Insulation Performance and Testing - About Insulation : NAIMA North American Insulation Manufacturers Association The Big Burn - YouTube If you can measure the heat that's hitting the foil, and it's under 450F, you might be good to go.. The no-contact heat scanners are what I use to measure surfaces. Attached Thumbnails __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

02-13-15, 12:08 AM	#21
ryanwc Lurking Renovator Join Date: Feb 2015 Location: evanston, il Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	Anyway, I just tested my hot water from the upstairs bathroom sink. 18 dumps of my 16 oz. cup got me to warm though not yet hot. To get actual hot water is surely 3 gallons per time. The pipe coming from the heater is always somewhat warm in the first few feet just from heat circulating up out of the heater itself, and I had thought it was uninsulatable because standard foam isn't recommended so close to high temperatures. I can't help but think if I could insulate it there, the insulation around the pipe running the rest of the way through the basement would stay warm, perhaps cutting in half the amount of water that had to be drained before I got warm or even hot water for my shower upstairs. I'm now realizing that fiberglass pipe insulation may be appropriate in this setting. Anyone have any experience, thoughts or concerns about fiberglass pipe insulation right next to the hot water heater smokestack?

02-13-15, 04:26 PM	#23
ryanwc Lurking Renovator Join Date: Feb 2015 Location: evanston, il Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	I went ahead and wrapped it with unfaced fiberglass, covered by foil tape. Though the EPA and others offer the bizarre advice to use unfaced fiberglass within 8 inches of the flue, but not to insulate within 6 inches of the flue, other sites that seem knowledgeable say you can use unfaced fiberglass closer; and the Home Depot plumbling guy felt it would be fine. The pipe runs parallel probably 3.5 inches from the flue. It's closer where the flue flanges outward as draftguard/indoor air intake, but that flange shouldn't get very hot, since it has indoor air flowing past it.

02-13-15, 07:25 PM	#25
mechanic Apprentice EcoRenovator Join Date: Aug 2014 Location: Saskatchewan, Canada Posts: 117 Thanks: 10 Thanked 16 Times in 12 Posts	When my house was built there was a pump and recirc line put in for the main and onsuite bathrooms as they are opposite side of the house as the utility room (~50'). It had a timer which was poor as my wife works shift work and I'm a day worker. It cost a fortune to run all the time as our water heater is electric and would run often, and with the pump off you would run the shower for five minutes before you got in and it would still be on full hot when you got out having never gotten that warm with all the heat loss and I suspect some backwards flow from the pumps return line on the cold feed side of the water heater... I ended up buying a bunch of cheap pipe insulation from Home Depot and insulated all the lines then I put a timed switch on the wall for the pump, just hit the button 30 seconds before you turn the shower on and it's instant hot then just turns itself off so nobody forgets it, works great!

02-13-15, 07:27 PM	#26
mechanic Apprentice EcoRenovator Join Date: Aug 2014 Location: Saskatchewan, Canada Posts: 117 Thanks: 10 Thanked 16 Times in 12 Posts	Oh and I also put a heat exchanger in the shower drains that acts on the incoming cold water to the showers, you gotta keep turning the hot water in the shower down as you go��

02-13-15, 10:56 PM	#27
ryanwc Lurking Renovator Join Date: Feb 2015 Location: evanston, il Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	The result of using about $1 of unfaced fiberglass wound around roughly 14" of pipe at the connection to the water heater, and then wrapping that in foil tape leftover from another project, was that the water was warm after about 270 oz. down the drain, vs. 318 oz. last night prior to the mini-project. (The pipe was already insulated with foam for another 20 feet, but with that 1-foot gap at the heater, the down-time heat that leaks up out of the heater was simply being lost, and the rest of the pipe would cool fairly quickly once a use was over.) It'll have a bigger percentage impact on the kitchen sink, which is closer to the water heater, and may also have a bigger impact in uses that come within 15 minutes of each other, since the pipe should stay warmer longer. It'll have more of an impact on my time than my budget by letting me step in the shower sooner, wash a dish sooner, etc. But it'll also pay for itself. Thanks, xringer, for the word of caution. I'll keep an eye on it, but I don't think it could get that hot.