Vent electric dryer to same room as heat pump HWH?
patrickcampbell
| Posted in Mechanicals on
I am curious if it would make any sense to vent an electric dryer inside instead of outside if you both were situated in a relatively dry basement with a heat pump hot water heater?
Let’s say you run a load of hot laundry. The Heat pump hot water heater kicks on to refill the hot water tank.
You switch clothes over and start the dryer which puts hot moist air into the basement. The heat pump HWH consumes both.
Would it work? Would humidity levels in the basement get too high? The heat pump is too slow to ward off humidity? Thoughts?
(For the record, we’ve had a heat pump clothes dryer and really did not like it. )
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I'm sure there's a tool or person who can do the calculations on sensible heat load and that, but instinct tells me that no interior HVAC system is ready to handle the heat AND humidity that comes from a dryer. Unless your basement has a dedicated HRV with dehumidifier, you're setting yourself for problems with mold, mildew, or just rust.
Fair enough. In our case extra heat is welcome for most of the year. So it comes down to humidity?
You also have to figure out how to deal with the lint.
DC,
And micro-plastics. From an IAQ perspective it's not a good idea.
Again, this is a completely theoretical discussion if it isn't code compliant.
Agree that it's theoretical.
Somehow ventless dryers manage to get the nasties out of the air.
On a theoretical basis I don't have a problem dumping the humidity into the house during heating season, most houses could use the humidity. What would make sense would be a baffle to vent during cooling season and keep the heat and humidity during heating season.
Obviously if a dryer is burning gas you need to vent the combustion products.
I would do it with a condensing "vent less" dryer. Mine dumps alot of heat into the interior.
How about a ventless heat pump dryer instead?
We had one and it was really bad. Very loud, and it broke in about 1 year, and didn't dry very well to begin with. When it broke, there was lint everywhere inside the unit. We changed the multiple lint filters on every use. Maybe they have made improvements since then.... I don't know.
patrickcampbell,
My reading of the IRC is that you are required to vent all ducted clothes dryers directly to the exterior. That's true of our code here too.
I put a make up air fan and heat exchanger on my dryer exhaust line to the exterior:)
Thanks, this seems like it would be the better option.... Most dryers (or no dryers?) do not have a place to hook up make up air, or do they?
This seems like it would be smart. I would be happy if it was simply a sealed process where it took outside air. I don't like how the dryer creates so much negative pressure in the house.
Back in the early 80's there was a bucket that had a top that fit the dryer hose. It had a vented top for the hot air to escape. The hot air was pushed into the bucket which held water. The water caught the lint and the hot air escaped into the room.
Personally, I think the humidity is going to be a huge issue in your case. The HPWH we have is very efficient. I think you're chasing pennies.
It is the moisture
you would need to have heat exchanger
If anyone has been in a room with a standard clothes dryer, there is enough heat going around to not want to open the exhaust up
gusfhb,
I once did some remediation on a two year old house where the dryer duct had not been hooked up, and instead dumped into the (poorly) vented crawlspace. It was humid, with mold problems on the underside of the sub-floor and walls, but also a lot like working in a damp room lined with felt. The volume of lint was astonishing to me.
My dryer is the bathroom and is vented outside. Even with taped joints, I get a surprizing amount of lint buildup on my ERV pickup filter about 2' from the unit. The rest of the ERV filters in the house have way less buildup. Even that little bit of lint would clog a heat exchanger over time.
I can't imagine dumping all the dryer vent into the same space and not having lint issues.
The last thing you want to do is a year or two down the road is have to take your heat pump water heater apart to scrub caked on lint from the coil. The filter on these units is nowhere near fine enough to capture all the lint.
I have a heat pump dryer. What's interesting to me is that the laundry room is actually less dusty than in my old house which had a conventional dryer. The new dryer, with a double filter, leaks less lint than my old dryer which was ostensibly venting it to the outside.
Mine is in the bathroom at work, I drained it into the toilet tank while I got the hookup pieces as it had the hook for a sink drain. All that lint is going down the drain. Wonder if we will see articles about fatbergs full of dryer lint in the future...