Vented tumble dryer and heat recovery ventilation

BarneyMc

This is what I've read about vented tumble dryers: "This is a vented machine, which means that the warm air from the drum needs to be vented away through a hose. You’ll need to have a wall vent or nearby window or door to hang the hose out of if you’re looking to buy a vented machine."

My new house has a mechanical heat recovery ventilation system and has, in the utility room (where the tumble dryer will live), an extract duct. Would it make sense to allow the warm air to feed into this and therefore allow the system to recover the majority of this heat instead of just venting out the window?

The Red Ace

but the air is also damp, will the moisture affect the other system.

If you want to extract the heat, you would be better off using a separate heat exchanger as mentioned by red ace, the air will be very damp.
Much damper than the extract from the showers,
I know that my system is mainly plastic so it would cope, but I use a vented dryer to avoid condensation in the ducts as the unit is quite a distance away.

BarneyMc

Deleted User wrote: »

If you want to extract the heat, you would be better off using a separate heat exchanger as mentioned by red ace, the air will be very damp.
Much damper than the extract from the showers,
I know that my system is mainly plastic so it would cope, but I use a vented dryer to avoid condensation in the ducts as the unit is quite a distance away.

I don't mean to duct it straight in... just to let the warm air be picked up by the HRV extract naturally.

Sorry confused now. Your system is mainly plastic - your ducts? You do use a vented dryer... so why can't I?

I should clarify that I have the dryer venting to the outside. Doing it the way you suggest should be OK.

GreenFolder2

No matter how good the vented dryer, you will clog the heat recovery ventilator badly with fluff if you pipe it straight in.

They're simply not designed for that and the dryer's filter meshes will not catch everything as they're designed to blow the air outside.

Also, if you vent it into the room, you'll cause serious amounts of moisture to condense all over the place.

You'd be better off getting a heat pump dryer or at the very least a good quality condenser dryer that will dump the heat (not the moisture, steam and fluff) into the room if you're using that level of heat-recovery.

Hoagy

You can buy a condenser box to catch the water vapour coming from the dryer, maybe that would work in your case too?


http://www.powercity.ie/?par=80-50-30025N

BarneyMc

GreenFolder2 wrote: »

No matter how good the vented dryer, you will clog the heat recovery ventilator badly with fluff if you pipe it straight in.

They're simply not designed for that and the dryer's filter meshes will not catch everything as they're designed to blow the air outside.

Also, if you vent it into the room, you'll cause serious amounts of moisture to condense all over the place.

You'd be better off getting a heat pump dryer or at the very least a good quality condenser dryer that will dump the heat (not the moisture, steam and fluff) into the room if you're using that level of heat-recovery.

Yeah, never intended to pipe it straight into the HRV duct.

So a condenser dryer still pumps out hot air but just without the moisture? I just assumed the hot air died when it was condensed to water. Then that's my best option - can someone confirm please?

GreenFolder2

BarneyMc wrote: »

Yeah, never intended to pipe it straight into the HRV duct.

So a condenser dryer still pumps out hot air but just without the moisture? I just assumed the hot air died when it was condensed to water. Then that's my best option - can someone confirm please?

Two types of condenser dryer and neither (if working correctly) release moisture into the room.

1) Traditional (cheaper) uses an air-to-air heat exchanger. There's a closed loop of air in the dryer - Hot moist air runs through the filters and into a heat exchanger. The constantly dryer blows air from the room through the heat exchanger and that cools the 'process air' and causes the moisture to drop out..

So it is constantly dumping quite large amounts of heat to the room to achieve this. They can output as much heat as a fan heater.

2) Heat pump dryer.
You're a closed cycle again, warm moist air from the dryer is passed through the cold side of the heat pump and this forces the water to rapidly condense out. Then it is returned to the drum via the hot side of the heat pump, effectively putting the energy back into it again. Very little extra heat is required.

Think of it as being like a dehumidifier in a closed loop, only with the air warmed up.

These are significantly cheaper to run and produce little or no heat to the room at all. However, the good ones are still fairly expensive.

BarneyMc

I won't be using the dryer very much - just to finish off damp clothes coming in from the line. I think a vented one would be fine for me. Also my HRV system can re-use the heat. Cheaper to buy also!