HWBB loop question

FredCapo

Hi. I have a first floor hwbb loop that is one zone on a 3 plus 1 indirect system. The zone loop is 80 ft that includes about 45 ft of slant fin 30 wuith remainder of loop 30 ft mostly 3/4 barrier pex with metal ribbed crimps. I want to add another 4 ft of slant fin a vestibule. A simple install would add about 10 ft of pex to the system, while drilling out joists would perhaps shorten the pex runs. Is this significant? The pex runs mostly in the joist pockets in unheated basement to boiler. The pex is not insulated at this point. Is pipe insulation recommended in either case? Thanks.

unclejohn

If the pex is below a condition space it is giving up some heat to it. If you shorten it you will lose that little bit of heat.

Ironman

As long as you don't add too many barbed fittings, there shouldn't be any significant difference.

FredCapo

Thanks for the comments. I was timid about bending the pex when I did the install so there are likely more ribbed elbows than necessary already. I plan to redo some of it in the summer with bends in place of elbows. What type of loss is caused by the elbows?

Ironman

Flow resistance, aka head loss. Reduce the flow too much and your btu output will be reduced.

hot_rod

I wonder how much pressure drop a barbed insert ell adds. Typically a copper or threaded 3/4 ell is equal to 5 feet of pipe. a long sweep is around 2.5 on the B&G Syzer calc..

With a fitting that reduces the ID I suspect it is a higher number, 6, 8, maybe 10 feet equivalent?

The copper insert ells are fairly thin walled. The brass and composite fittings seem to present more reduced ID.

for baseboard the PAP of Viega FostaPex work well as they hold their shape and don't put stress on the connections.