Insulating hot water recirculation pipes
robca
| Posted in Energy, Heating & Insulation on
I’m getting a hot water recirc system installed in a new construction. The system is PEX tubing.
Do you need to insulate the hot water lines? I’m assuming it would lower heat waste, but I’m also wondering about places where hot and cold pipes run side by side: will the cold water get warmer as a result of having pipes close by, or is it not a problem with PEX usually? I’m sure it would be a problem with copper
Thanks in advance, Rob
Replies
Greetings robca,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again.
Perhaps it will catch someones attention that can help you with advice.
Cheers
"Live Free,
not Die"
Yes, you want the whole run to be insulated. (Except bends and transitions, etc). The one exception would be a 90%+ heating season, like in Barrow or Nome. Then the lost heat is all utilized productively.
Even if uninsulated, you won't have a huge a temp rise in those wall cavities - air is a poor conductor of heat and those bays are pretty high. And with that piping insulated, the cavity might only be 5F above ambient. So initially cold water would come in at 75F instead of 70. You still have to let it run the same amount if you want it to be really cold. And with 1/2" homeruns, that cold water will get to the fixture faster than with tradition copper layout (3/4" to each room feeding 1/2" to each fixture). But you might as well run the hot piping above the cold to minimize that effect.
And if he has RFH, he will wanna insulate the cold, too. Ask me how I know...
ok, how?"Live Free, not Die"
Due to parenthood and real work, I had to sub the plumbing on our RFH cabin. But the 1/2" PEX homerun was down in the sand and only 8 feet to the bathroom and 14 feet to the kitchen. Gets pretty cold pretty quick. But then, it comes in at 38F.A longer run and/or in the concrete, yes, you'd never have really cold water.Jim, one I've wanted to try is a 3/4" PEX run in the RF to feed the HWH. So it sees 80 or 85F incoming instead of 45-50F (38 for me). That would help the first hour and recharge rate a lot AND reduce the corrisive condensation occurring in the HX.Robbing Peter to pay Paul, but if I'm in the shower, the extra 20 gallons of HW is more important than dropping room temps by about 0.2F.David Thomas Overlooking Cook Inlet in Kenai, Alaska
We have 2 different recirculating loops in our house. One goes east from the water heater, one goes west.
When we moved in, the loops didn't appear to work at all. So we insulated the hot side of it, thinking that would help. The hotter the hot side is, the more flow there would be.
Can't say as I can see any difference at all. Every once in a while I get surprised with hot water right away. But 95% of the time it doesn't appear to do anything.
To provide further info: my PEX system is not using Manablock or similar. It's just a traditional house run, with 3 ways splitters here and there where it needs to branch. After following the pipes, I saw that in many places hot and cod run side by side (in contact). I'm concerned that, after a few hours with hot water recirculating and no cold water running, the cold water might be much warmer than room temperature. I know that insulation only slows heat transfer, doesn't prevent it, but it seems like a good thing to have anyway.
Reading Vanguard's material, it looks like bundling together hot and cold is ok for a Manablock system, but doesn't say anything about a traditional house run. I'm still a bit puzzled by the whole thing...
Thanks for all the answers, btw