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How many devices is safe enough to discharge drain water into your floor drain pipe (Furnace Room)

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Penalty Box
Jun 24, 2015
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How many devices is safe enough to discharge drain water into your floor drain pipe (Furnace Room)

I have 5 peace's of equipment in my furnace room which have drainage hoses connected to them.

Water tank, HRV, Furnace drain - goes into pipe going into the floor
AC Condenser and Humidifier have a separate drain hose which goes up to the floor drain cover and simply sits on top of it.

The problem is if someone goes in the furnace room they may step on or move that hose and I will end up with a puddle of water.

I was thinking about finding ways to secure that hose but should i be safe to connect all 5 devices to the pipe coming out of the ground? I just need some extra Tee Fittings and can do it but is it recommended to have that many?

I cant find any documentation or law or rules which says how many is too much?

its highly unlikely they will all discharge water at the same time,. in the summer the AC condenser usually is my problem, if someone trips over that hose and it gets moved i have a nice puddle that i step into and its not nice.
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22 replies
Deal Fanatic
Dec 19, 2009
5139 posts
3275 upvotes
Well your main sewer line is probably 4" and your floor drain is probably 3" so maybe count how many things are going into you main sewer line and then that might give you an idea of how many things can go into your floor drain.
Deal Fanatic
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Oct 15, 2007
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Your basement floor drain(s) is almost always 4”. The hydraulic load for a 4” trap is 6 fixture units. More than capable of handling the condensate from the listed appliances


Are you thinking of tying all of the lines to the 5/8” poly that comes out of the ground that leads to the floor drain?
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Member
Nov 30, 2015
433 posts
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GTA, ON
I use cable ties to secure the hoses to each other and to the floor drain.
Deal Addict
Sep 13, 2016
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Mississauga
lazybummer wrote: I use cable ties to secure the hoses to each other and to the floor drain.
I have the same setup. All tied with cable ties.
[OP]
Penalty Box
Jun 24, 2015
7189 posts
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Red_Army wrote: Your basement floor drain(s) is almost always 4”. The hydraulic load for a 4” trap is 6 fixture units. More than capable of handling the condensate from the listed appliances


Are you thinking of tying all of the lines to the 5/8” poly that comes out of the ground that leads to the floor drain?
Yes im thinking about using the 5/8" poly that comes out of the ground that leads to the floor drain, is there a special name for this? i just need an extra Tee (T) fitting from home depo to make it work, right?
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Deal Addict
Nov 7, 2012
1439 posts
769 upvotes
TORONTO
ugh... just cleared out my A/C condensate line as it was backed up leaking water through my furnace.
I took off the drain cap/grate and shoved all the pipes down there.

A few years back there was a thread on this same topic. There was a product that had connections on the drain cap for tubes and what not. Basically similar to using zip ties to secure the tubes to the drain.
Member
Aug 22, 2012
387 posts
369 upvotes
Mark Town
I hard plumbed most devices using 1/2" and 3/4" CPVC. It is much better than the poly hose solution. Especially I have a water softener which releases a lot of pressurized water at regeneration. Those pipe lead to another drain pipe. Right now only furnace and dehumidifier uses the floor drain.
Deal Addict
Nov 17, 2012
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Toronto
Your main drain line is sized to manage the output of every single plumbing fixture in your house turned on full at the same time without backing up.

Don't over think the few low volume intermittent drains you have running into the floor drain.
Deal Addict
Jun 16, 2009
3788 posts
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Woodbridge
Thank you @Red_Army . Something new to learn everyday. Does Furnace and AC counted as two appliances even though when furnace works , AC can't work and viceversa ?
Red_Army wrote: Your basement floor drain(s) is almost always 4”. The hydraulic load for a 4” trap is 6 fixture units. More than capable of handling the condensate from the listed appliances


Are you thinking of tying all of the lines to the 5/8” poly that comes out of the ground that leads to the floor drain?
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[OP]
Penalty Box
Jun 24, 2015
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newlyborn wrote: Thank you @Red_Army . Something new to learn everyday. Does Furnace and AC counted as two appliances even though when furnace works , AC can't work and viceversa ?
I am guessing yes. not sure if you noticed but most hi efficiency furnaces has its own condensate drain line that is separate from the air conditioner condensate drain line, I don't really know why or how a hi efficiency furnace needs one but since my old furnace was a low efficiency one and this new one is a hi efficiency, there must be some reasoning behind it, but yes one extra pipe to connect to the plumbing
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Deal Fanatic
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Oct 15, 2007
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newlyborn wrote: Thank you @Red_Army . Something new to learn everyday. Does Furnace and AC counted as two appliances even though when furnace works , AC can't work and viceversa ?
Fixture unit is a plumbing term for hydraulic load that is imposed on a drain or trap. It is not directly synonymous with the number of appliances that it may accept.

To calculate the hydraulic load for a trap in regards to an air conditioner for instance , you would have to know Litres per second flow rating of the appliance in order to calculate and translate to drainage fixture units.


Confused yet? Plumbing is easy right? Just putting pipes together and changing washers lol
Everything has been said before, but since nobody listens we have to keep going back and beginning all over again. - Andre Gide
Deal Fanatic
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Oct 15, 2007
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torontotim wrote: Your main drain line is sized to manage the output of every single plumbing fixture in your house turned on full at the same time without backing up.

Don't over think the few low volume intermittent drains you have running into the floor drain.
Close.

They’re sized to carry no more than 65% of its full capacity
Everything has been said before, but since nobody listens we have to keep going back and beginning all over again. - Andre Gide
Deal Addict
Jun 16, 2009
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Woodbridge
LOL. I thought I know quite a bit since I can change dip tubes, repair copper joints and can put pipes together when installing water heaters.
You nailed it.
Red_Army wrote: Confused yet? Plumbing is easy right? Just putting pipes together and changing washers lol
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Deal Addict
Oct 19, 2020
1048 posts
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GTA
One thing to consider is that if the a/c condensate line is not trapped when the coil is installed above the furnace(most are not), there will be air being pushed down the that line when the furnace fan is running.

On the other hand, the furnace condensate line is always trapped and upstream of the trap is negative pressure.
I could see interference with proper drainage of the furnace when the same line is used for the a/c.

So imo it is better to keep the furnace condensate line separate.

The volume/flow rate of water combined normally should be far lower than what a regular faucet flows.
Hvac advice warning - inaccurate information on forum, vested interests in selling builder's equipment. Selling dealer-only brands without being authorized is a red flag. Report to CRA if offered no tax cash-deal. If it's 2 good to b tru, it is.
[OP]
Penalty Box
Jun 24, 2015
7189 posts
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not sure what negative pressure is, water drips from the coils and collets into a pan, it drains out of the side of the duct work into a hose that is sitting on top of my floor drain, and often into a puddle in my furnace room if someone trips over the hose and it gets moved

I am simply removing the tripping hazard and the potential for a puddle and eliminating it by wanting to connect it to a hose that is alredy going into the floor drain, im sure there is a trap in my floor drain already so I dont get this whole no trap thing? the floor drains always have water in them, well atleast mine does
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PEACE is the answer!
Sr. Member
Dec 6, 2020
937 posts
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GoodFellaz wrote: I don't really know why or how a hi efficiency furnace needs one
High efficiency furnaces extract so much heat from hot gasses created during combustion that water vapor in the combustion gases condenses into liquid water. This water has to be drained, hence the need for a condensate drain.
[OP]
Penalty Box
Jun 24, 2015
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cool, and what is this about negative pressure? does my AC condensate actually need a U trap, or P trap or what ever they call it?
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Deal Addict
Oct 19, 2020
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GTA
GoodFellaz wrote: not sure what negative pressure is, water drips from the coils and collets into a pan, it drains out of the side of the duct work into a hose that is sitting on top of my floor drain, and often into a puddle in my furnace room if someone trips over the hose and it gets moved

I am simply removing the tripping hazard and the potential for a puddle and eliminating it by wanting to connect it to a hose that is alredy going into the floor drain, im sure there is a trap in my floor drain already so I dont get this whole no trap thing? the floor drains always have water in them, well atleast mine does
Negative pressure in layman's terms is suction, positive, blowing out.

The furnace itself has a trap in it to allow water to drain properly by preventing air from being sucked in.
The a/c coil has a drain line, and it is under positive pressure - air blowing out whenever the blower is on

The air blowing out can interfere with proper furnace condensate drainage.

Please keep the furnace condensate line completely separate from a/c drain line. These should not share the same common condensate line - doesn't matter where they connect.
Hvac advice warning - inaccurate information on forum, vested interests in selling builder's equipment. Selling dealer-only brands without being authorized is a red flag. Report to CRA if offered no tax cash-deal. If it's 2 good to b tru, it is.

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