Trunk line size - Weekend project

Users who are viewing this thread

OliG

New Member
Messages
7
Reaction score
0
Points
1
Location
Quebec
Hello,
I just completed a full house remodel and all went (relatively) fine, but as always, little annoyances reveals themselves after all is done, when you live in the house.

One problem I have is the wait time for hot water in one bathroom. I ran 3/4" pex trunk lines the full lenght of the house to get adequate volume to all fixture. Fresh water comes from a well and then pass throught a water softener, so pressure is lower than a house feeded by city water, hence the choice to use 3/4" pex trunk lines. I have good volume now, but the farther bathroom takes forever to get hot water. This is easily explained as the cold water in the line must first flow to be replaced by hot water. The trunk line is around 70 feets from water heater to the end of line. I knew this when I opted for the 3/4" diameter, I just didnt expected the wait time to be so long.

My question is then should I replace the hot water trunk line for 1/2"? Will I see a drastic improvement or will it only be marginal? Is it ok to have 3/4" for cold and 1/2" for hot?

I know 70 feets is a long run so I'm also considering adding a second water heater near the remote bathroom... Is this a crazy idea?

Thank you for all advices !
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
Are you mostly concerned about the faucet or also the shower? One possibility is to home-run 3/8 to the hot tap on the lavatory. That should get hot about 4 times faster.

You could also use a recirculation system to keep the water in the pipe hot.

Second or auxiliary water heater is not crazy.
 

OliG

New Member
Messages
7
Reaction score
0
Points
1
Location
Quebec
I'm concerned with both i guess... If I understand correctly, I would home run 3/8" to faucets wich would reduce wait time for faucets, and keep the 3/4" Trunk to the shower and to bath? Or do you mean home run hot in 3/8 to all fixtures requiring hot water of the bath group (2 lavs, one shower and a bathub)? Is 3/8 enough for a shower with 2 heads?

what about the 1/2" trunk line? Hardware stores around here do not sell 3/8" pex...

I would prefer to avoid recirculating system if others options are availables, as I read than they waste more power than a water heater alone.

Thanks !
 
Last edited:

Gary Swart

In the Trades
Messages
8,101
Reaction score
84
Points
48
Location
Yakima, WA
A recirculating system works great. It requires a return line and pump, but if running the return line is not too difficult, it's a very doable method. Not overly costly.
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
First, I am not experienced in this. I have read some things, and I was hoping to give you some ideas to research or think through further. Many people run a manifold with smaller home-run pipes to at least the hot fixtures. I feel confident that 3/8 would give plenty of water volume for the sink. However I don't know about the shower. I think to figure that that would require some pressure drop tables, knowing the water pressure in your system, and knowing the water consumption of the shower heads. And I don't know if delay on the shower bothers you more than the delay for the sink.

If you have a tempering valve at the water heater, that is hurting this too. If the tempering valve serving the bathroom were relocated to the bathroom, that would increase the hot water pipe flow to give you hot water at the bathroom sooner. I would expect the speed improvement to be roughly the percent of cold that is being mixed in at the water heater. I can't put numbers on it, but the hotter your water at the heater, the bigger that effect.

Regarding circulation, some people put the pumps on a timer.
 

LLigetfa

DIYer, not in the trades
Messages
7,497
Reaction score
575
Points
113
Location
NW Ontario, Canada
Fresh water comes from a well and then pass throught a water softener, so pressure is lower than a house feeded by city water...
Why can you not have higher pressure with a well? A properly designed system can produce better pressure than many municipal water systems.
 

Craigpump

In the Trades
Messages
2,436
Reaction score
158
Points
63
Location
Connecticut
There's always some pressure loss through a softener, but that's easily rectified with a 3/8 nut driver.
 

OliG

New Member
Messages
7
Reaction score
0
Points
1
Location
Quebec
We tought than the pressure was inadequate with the old piping and fixtures... Now than we replaced almost everything starting at the water softener, the pressure and volume are good. This is why I consider replacing a section of the trunk to a smaller diameter pipe. I would replace a section that deserve only a bath group, 2 exteriors faucets and a utility sink. I would keep 3/4" trunk to kitchen and then reduce to 1/2" for the rest of the run, around 50 feets.

I did some researchs and I do now consider a recirculating system, as a plumber told me than they generally install this kind of system when they encounter my problem. Installing the return line would be easy as the basement is unfinished, so I'm more concerned with the cost to operate than the installation.

Is the recirculating system the best alternative?
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks