HRV Ducting Dripping water

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Azazel

5 posts

Wannabe Geek

#315474 20-Jul-2024 10:18

Hello all,

I have been a member for about 5 years and read the forums on a regular basis and find some of the discussions really interesting and full of useful information.

That said, I have an issue with my HRV (about 6 years old now) which is dripping water from one of the outlets (sadly enough is the one oin the master bedroom) and not from the other three outlets.

I did check the forums in case anything like this had been discussed in the past and could not find anything; however, if this has been discussed before I totally apologise to all.

My steps so far:

1 - Contacted HRV and was told that water moisture would have accumulated in the ductwork and now I would need to replace them all - which I find puzzling, to be honest.

2 -Removed the outlet from the ceiling and indeed a fair bit of water came out of the duct.

My questions are, has anyone come across this before, and if so what was done to avoid the recurrence of this issue? Also, does it not seem counterintuitive that a system designed to remove excess moisture from one's home actually fills with the same?

Finally, if I switch the system off and close shut the outlets will it stop the building of condensation or would I risk that it will fill up overtime and then have a disaster happen?

Any insight, advice, or even food for thought wouldbe greatly appreciated.

Warmest regards

Roberto

tweake

2391 posts

Uber Geek

#3261753 20-Jul-2024 11:26

not a problem i have heard of happening.

the water will be from condensation, so its matter of working out why that's occurred and why it hasn't dried out.

so, what part of the country are you in? just to get some idea of what temps are like.

what type of house construction do you have? what age home? do you have a crawl space under the floor and do you have any brick cladding/walls ? what sort of ceiling do you have?

Bung

6480 posts

Uber Geek

Subscriber

#3261803 20-Jul-2024 12:55

tweake:

not a problem i have heard of happening.

the water will be from condensation, so its matter of working out why that's occurred and why it hasn't dried out.

what type of house construction do you have? what age home? do you have a crawl space under the floor and do you have any brick cladding/walls ? what sort of ceiling do you have?

Isn't the HRV thing to take ceiling space air and pump it into the house? Why would the crawl space be a factor?

What is the roof made of? If only 1 outlet is dripping water is there any chance that there is a leak in the roof running down 1 branch of the ducting?

tweake

2391 posts

Uber Geek

#3261807 20-Jul-2024 13:08

Bung:

tweake:

what type of house construction do you have? what age home? do you have a crawl space under the floor and do you have any brick cladding/walls ? what sort of ceiling do you have?

Isn't the HRV thing to take ceiling space air and pump it into the house? Why would the crawl space be a factor?

in some homes, ie with brick walls and crawl space, the ceiling space and crawl space are connected via a ventilation gap in the wall. ie the wall is brick outside, then a 2" gap, then wooden wall. so moist air from the soil under the house can go up that gap into the ceiling space (normally gets ventilated out through the roof), which then gets sucked into the ventilation system, which puts a lot of moisture in the house. they are meant to have an external air intake ie not use ceiling air.

now sometimes you get a house thats mostly concrete pad but has a little bit of crawl space. that still can put moisture through the ventilation system.

damp air getting sucked into cold ventilation ducts can cause it to condensate inside the ducts.

Azazel

5 posts

Wannabe Geek

#3261811 20-Jul-2024 13:26

Thank you both for your replies.

So, the house is stucco, mid sixties, in Napier.

It does have a ceiling crawl space, which I have used to replace the HRV filter on several occasions.

The house also has an under floor crawling space.

Last year I had the ceiling and underfloor insulation replaced, also the moisture protection sheet under the house.

To answer the other theory, yes it is something I thought right away and went up into the ceiling as a first port of call, and no evidence of leaking anywhere.

When I spoke to the HRV tech on the phone he asked me if I had switched the system off over summer, which I regularly do every year, since the system is designed to remove the relative humidity from the house which condenses in winter. Also in summer the system throws out hot air from the roof cavity making sleeping unbearable.

So, the story I have had from HRV is that because the system is designed to run 24/7 and I have switched it off I have created the issue, in essence.

However, my previous home had a DVS for 14 years and although I have always switched it off in summer I have never experienced this issue.

Do you think that I could just turn it off and get along with my life without issues?

tweake

2391 posts

Uber Geek

#3261821 20-Jul-2024 14:01

Azazel: Thank you both for your replies.

So, the house is stucco, mid sixties, in Napier.

It does have a ceiling crawl space, which I have used to replace the HRV filter on several occasions.

The house also has an under floor crawling space.

Last year I had the ceiling and underfloor insulation replaced, also the moisture protection sheet under the house.

To answer the other theory, yes it is something I thought right away and went up into the ceiling as a first port of call, and no evidence of leaking anywhere.

When I spoke to the HRV tech on the phone he asked me if I had switched the system off over summer, which I regularly do every year, since the system is designed to remove the relative humidity from the house which condenses in winter. Also in summer the system throws out hot air from the roof cavity making sleeping unbearable.

So, the story I have had from HRV is that because the system is designed to run 24/7 and I have switched it off I have created the issue, in essence.

However, my previous home had a DVS for 14 years and although I have always switched it off in summer I have never experienced this issue.

Do you think that I could just turn it off and get along with my life without issues?

i think those stucco houses where direct fix, so there should not be a connection via the wall. but might pay to check beside the fireplace. sometimes the can extend the fire place cavity right down under the house.

ventilation systems should on all year around. they also should turn off when they get to hot. they should always run even when really cold, otherwise warm moist air can flow back up the ducts and condensate inside the ducts. however even if this happens, once its back on it should dry out. but it may be its a long run, low airflow and condensation is exceeding drying. i would check that air is coming out on a cold night/morning. if its stopping, then that certainly could cause condensation issues. then check controller settings. not sure with those but check its set to still run when cold.

its not uncommon for people to make the ventilation systems stop when its cold because they think its cooling the room down. its more of a perception problem. one of the reasons many systems cannot be turned off on the panel (or can but restart after some time).

gzt

17118 posts

Uber Geek

Lifetime subscriber

#3261843 20-Jul-2024 15:46

Q: What did the heatpumps say to the HRV system? I'm not a fan.

its not uncommon for people to make the ventilation systems stop when its cold because they think its cooling the room down. its more of a perception problem.

Windchill is real if relatively minor in some cases

tweake

2391 posts

Uber Geek

#3261845 20-Jul-2024 15:57

gzt:
Windchill is real if relatively minor in some cases

translation please

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gzt

17118 posts

Uber Geek

Lifetime subscriber

#3261848 20-Jul-2024 16:05

Wikipedia: Wind chill (popularly wind chill factor) is the sensation of cold produced by the wind for a given ambient air temperature on exposed skin as the - air motion - accelerates the rate of heat transfer from the body to the surrounding atmosphere. Its values are always lower than the air temperature in the range where the formula is valid. When the apparent temperature is higher than the air temperature, the heat index is used instead.

RunningMan

8955 posts

Uber Geek

#3261850 20-Jul-2024 16:06

Le refroidissement éolien est réel bien que relativement mineur dans certains cas

tweake

2391 posts

Uber Geek

#3261868 20-Jul-2024 16:48

gzt:
Wikipedia: Wind chill (popularly wind chill factor) is the sensation of cold produced by the wind for a given ambient air temperature on exposed skin as the - air motion - accelerates the rate of heat transfer from the body to the surrounding atmosphere. Its values are always lower than the air temperature in the range where the formula is valid. When the apparent temperature is higher than the air temperature, the heat index is used instead.

o funny man.

there is no real winchill if its done right. vents should not be over the top of setting and the vents fire sideways so the air flows along the ceiling (and down behind curtains, but thats another story).

the only way they notice the cold air is if they put their hands up by the vents and feel that its cold. they feel the cold therefore it must make room cold, so they block it off. but in reality that small amount of cold air makes stuff all difference to the room temp. so they have disabled the ventilation for a perceived problem that does not exist. its a common problem in low end rentals.

the same issues arise with keeping windows open for ventilation. its cold outside so they shut the windows and then wonder why they have moisture problems.

raytaylor

4014 posts

Uber Geek

Trusted

#3265124 27-Jul-2024 13:31

Our HRV system in napier doenst have this issue.

The only way I could see it happening is if the outside air intake is bringing in moist air at dusk, into an attic that is colder and causing the moisture to condense on the walls of the duct which is never the case - the attic is always hotter than outside.

I also turn ours off if its too hot or too cold.

I always keep mine set to the goal temperature of 28 so it heats the house during the day and then the mass inside the house (furniture, objects, etc) can release that heat into the evening when we arrive home, ready for the heat pump and storage heaters to take over at 9pm when the contact free power starts.

So if its not daytime, i have it switched off.

My suggestion is to continue looking for a leak. It might mean you need to cut open the ducts at the halfway point to work out where water exists or doesnt, and then further your search in the direction towards the source. Though water could flow in both directions.

Alternatively maybe put a shoebox under the duct to lift it up and create a point where the water wont pass and then determine over time which side the water exists on.

I wonder if its just a roof leak which is getting into the duct when its wet and the airflow caused by the hrv is causing the attic around it to dry up quite quickly.

Ray Taylor

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Azazel

5 posts

Wannabe Geek

#3265195 27-Jul-2024 17:45

Thank you, Ray, for the useful information.
Yes, I agree there must be more to it, and even though I have been up there with a fine tooth comb and couldn't see any leaks, it may pay to get a roofer to have a proper look.

I am just baffled by the HRV tech's response over the phone advising me that the reason for the dripping was to do solely on my turning off the system during summer.

Thank you again for the help everyone.

tweake

2391 posts

Uber Geek

#3265288 27-Jul-2024 21:03

I am just baffled by the HRV tech's response over the phone advising me that the reason for the dripping was to do solely on my turning off the system during summer.

they are mostly sales people. off in summer won't cause an issue. off in spring/autumn will cause issues. warm enough to keep the system off but ceiling temps dropping down enough to cause condensation. of course its the bedroom as bedrooms are humid because your in there and at night when ceiling is cold. moisture plus cold ducts.

i would just leave the system on and make sure the settings are correct.