Bringing condensate drain through unfinished attic space

Hitchum

Hey all,

I am installing a mod-con boiler in a mechanical room that doesn't have a drain, and am planning to pump neutralized condensate into the kitchen drain. The kitchen is located about 15' away on the same level, but I will need to route the drain line through attic space and inside walls.

I don't like the idea of installing vinyl tubing in inaccessible spaces, so was planning to install dishwasher outlet boxes on either end, with 1/2" PEX connecting them (i.e., one box in the mechanical room, and one box under the kitchen sink) . Then I would make up appropriate fittings to connect the condensate pump to the outlet in the mechanical room, and the box in the kitchen to the sink tailpiece via a drain saddle (similar to those used for RO water treatment).

Would love to hear any feedback on this idea or how you have handled similar situations.

TIA!

Niall

EBEBRATT-Ed

don't know what a DW outlet box is but you plan of using pex sounds fine to me.

pecmsg

Can this space get below freezing?

HVACNUT

The mechanical room doesn't have an exterior wall? It wouldn't be easier to discharge to outside?

Jamie Hall

If that space gets below freezing, I'd seriously want to heat trace that line. Otherwise, it will freeze and will plug up…

Hitchum

Thanks all. @EBEBRATT-Ed a DW outlet box is basically just a stub out with a valve and 3/8 compression fitting, but recessed in a wall box (example from Oatey). The only reason I'm using them instead of regular stub outs is that wall clearance is an issue in both rooms.

@HVACNUT the only exterior wall is a low sloped roof :-/ Considered discharging to the roof with a heat trace on the line but that seems less robust than routing on the interior

@Jamie Hall @pecmsg good point that it might freeze internally too. the attic is not particularly well insulated but it could be a concern. I will plan to insulate the PEX and ensure the pump can cut off the boiler if not the reservoir isn't emptying.

pecmsg

please check

Can heat tape be used with PEX ?

Frost Tex is the heat tape I use in walk in freezers. It can be cut to length, overlayed on itself, self regulating and I’ve never had to replace it in over 30 years

DCContrarian

Condensate lines gunk up and get clogged and then the furnace shuts down. Usually on Friday night on the coldest day of the year.

I don't like 1/2" PEX for that application. First, it's awfully small and will be prone to clogging and hard to unclog. Second, it won't be straight and there will be "belly" where water collects, which will be prime breeding ground for the kind of gunk that clogs those lines. Our code requires concealed condensate lines to be 3/4" minimum and a rigid pipe like PVC.

For tying into the kitchen sink, if you don't have a dishwasher get a dishwasher tailpiece and connect to that.

Hitchum

@pecmsg Thanks for the recommendation on Frostex. Their installation guide includes a table for plastic pipe so I think it should be usable with PEX (the brand I'm using has a max temp of 180F)

GroundUp

https://forum.heatinghelp.com/discussion/comment/1811824#Comment_1811824

Small? All residential condensate pumps use 3/8" or smaller. 1/2" PEX is more than adequate for pumped condensate

Hitchum

@DCContrarian Yeah. A gunked up line sure would be a hassle.

NYC 314.2.2 allows PEX tubing for condensate disposal, but does require a continuous slope, and at least 3/4" ID pipe to the "place of condensate disposal". Condensate pumps typically accept 3/4" PVC to the reservoir, and have a barbed outlet for 3/8" vinyl tubing. So it's hard to see how you install one and still meet code. I guess you could make the argument that the pump reservoir is the "place of disposal"

To help manage any gunking up and improve flow, I will install hose fittings either end instead of 3/8 compression valves, and also sleeve the PEX in PVC so it's a straight run. The hose fittings will allow me to disconnect the pump and blast mains pressure water through to try and and clear any jams (… or, even better, run hot water through at the start of every heating season). They will also make the hookup to the pump and sink drain a lot easier.

There is a dishwasher already hooked up to the sink tailpiece. I can't find any dual branch tailpieces, but luckily there is enough room for an old school washing machine tee, so I'm planning to install one of those for the condensate discharge.

ratio

I'd be a little concerned with brass in contact with the acidic condensate.

I think I'd look at sleeving the vinyl tube in PVC to keep it from bellying and insulate that with Armaflex. A heat trace could run along inside the PVC too, if needed.