Indirect piping size

skalor

Going to be plumbing in a Weil-Mclain Aqua Plus 45 indirect and was debating a couple things. It has 1" taps for the boiler feed and return but would I get more output from 1 1/4" piping. Boiler is a LP Crown at 117,000 btu output with 1 1/4" taps. The WM lit states that the indirect coil is bigger than 1" internally and lists the head at 3.3'. Going to make the piping as short as possible, shooting for a total of 10' with maybe 5 or 6 90°s. Would a 007 be too small, should I step up to a 010? The kids are getting older and I would like unlimited hot water if possible. Shower heads are both 2.5 gpm but only one will be running at a time. Boiler has DHW priority and I'm running a 120 gallon buffer so that gives me a little headway on the heating side for when I need DHW production. Initial calculations say I should be good for unlimited DHW. It should take 18.8 minutes to fully recharge the indirect to 160°, (40 X 8.34 X 110)/117,000 = .31(60) = 18.8 mins. I think the 1" lines may limit the heat transfer potential and since I have no experience in this arena I figured I would ask the experts.

Robert_25

1" and a 007 should be fine. The WM manual calls for 8 gpm.

EBEBRATT-Ed

1" is good with the 007. Your run is short so increasing to 1 1/4" will not help.

NY_Rob

You don't want to heat the indirect to 160F if I read your intentions correctly. High temps like that promote scaling on the tank's heating coil and will shorten tank life. Generally 140F is considered high enough (of course a mixing valve must be used too at 140F).

skalor

Robert said:

1" and a 007 should be fine. The WM manual calls for 8 gpm.

EBEBRATT-Ed said:

1" is good with the 007. Your run is short so increasing to 1 1/4" will not help.

Sweet, saves me a little cash since I aldready have an 007 sitting around after I replaced it with a Grundfos Alpha.

NY_Rob said:

You don't want to heat the indirect to 160F if I read your intentions correctly. High temps like that promote scaling on the tank's heating coil and will shorten tank life. Generally 140F is considered high enough (of course a mixing valve must be used too at 140F).

That makes sense since continuous dhw production shouldn't a be problem, no sense storing higher than necessary. My current direct fired water heater is original to the house from 1991 and dhw ouput is still great but not enough for when I have teenagers and I still want a hot shower. haha

HVACNUT

Or you could change your thinking completely. Look at a Turbo Max 23 reverse indirect. It will out perform the WM tank by far. It needs 9 GPM with 1 1/4" supply and return. Set to 140, pipe in the thermostatic mixing valve set to 120. I always piped in a 3/4 x 1/2F x 3/4 fitting and installed a well thermometer on the domestic out.

One thing I periodically seem to come across is the lack of a domestic relief valve on the Turbo Max (From the installer). Don't mistake the 30 lb relief for domestic.

skalor

<blockquote class="Quote" rel="HVACNUT">Or you could change your thinking completely. Look at a Turbo Max 23 reverse indirect. It will out perform the WM tank by far. It needs 9 GPM with 1 1/4" supply and return. Set to 140, pipe in the thermostatic mixing valve set to 120. I always piped in a 3/4 x 1/2F x 3/4 fitting and installed a well thermometer on the domestic out.

One thing I periodically seem to come across is the lack of a domestic relief valve on the Turbo Max (From the installer). Don't mistake the 30 lb relief for domestic.</blockquote>



I actually wanted an Ergomax or a Turbomax to utilize as a buffer and for DHW but I got a good deal on a Bradford White 120 gallon tank a couple tears ago. I have the LP boiler in parallel with a pellet boiler so I wanted a bigger buffer for the pellet boiler hence the 120 gallon tank. The WM indirect is used, from 2014, and was taken out because the owners wanted to switch to forced air for some strange reason. Haha

Henry

Each 1 " 90 is equivalent to 5.2 feet. 1" the max normal flow is 8 GPM.

skalor

So my water heater from 1991 died the other day which moved up the time table for the indirect.



The 007 and 1" works great with the aqua Plus 45. Did a quick job on the domestic side because I worked on this instead of sleeping yesterday, I work third shift, so I just threw pex at it for now.



Everything worked out great and having an endless supply if hot water while saving on fuel is great. This board is awesome and I've learned so much just reading.

flat_twin

Great timing with an indirect plus parts ready to go. Were there any signs your water heater was about to fail?

skalor

> @flat_twin said:
> Great timing with an indirect plus parts ready to go. Were there any signs your water heater was about to fail?

Never saw any leaks and hot water output was still good. It been making me anxious since we bought this house in 2014. Kinda amazing that it lasted 27 years though.