What min temperature setting to use for Smartvent (or similar) over winter?

Forums › Home Workshop DIY › What min temperature setting to use for Smartvent (or similar) over winter?

1 | 2

Froglotion

208 posts

Master Geek
+1 received by user: 78

#2478334 6-May-2020 23:39

Doesn't matter how much you heat a house, it doesn't solve the condensation problem.

I'll give you an example.

My first place (built it 2007, so doubled glazed, fully insulated, sealed box), put in one heatpump (small house but also couldn't afford two). Used to get bad condensation in master bedroom as had ensuite. So two showers per night, plus all of the moisture from just sleeping equaled bad condensation. Thought i'd get a heatpump for the bedrooms. They got a lot warmer, but condensation problem was the same. Hmmm. Spoke to someone who designs HVAC on a huge scale. They said on a budget, positive pressure ventilation would solve the problem, but would introduce cold air in winter. Installed a "Drymatic" basic system, condensation was gone in days, maybe 1% of previous condensation left. The difference was night and day, the house dried right out. The only thing I had to changed was put the heatpump on timer to come on in the morning. I didn't care if it was cold after I went to bed. So spent a bit more on heating, but never had condensation again. A good budget result.

dejadeadnz

2394 posts

Uber Geek
+1 received by user: 2287
Inactive user

#2478336 6-May-2020 23:43

Handle9:

Gross generalisations follow:

New Zealand houses are junk. Until relatively recently houses were single glazed, uninsulated and didn't have heating. New Zealanders don't heat their houses, they heat their living rooms.

In other parts of the world they heat / cool the whole house, not just single rooms. PPV is lipstick on a pig.

A million times this. Plus most people are blind to a few fundamental realities:

1. A proper indoor temperature matters. Leaving the house freezing cold will cause condensation problems, even in modern/double-glazed and well insulated (by NZ standards anyway) houses.

2. Double-glazed and insulated houses (especially if just built to Building Code) alone almost certainly won't be enough to free one from condensation problems year round, if you live south of Auckland and refuse to invest in proper heating solutions.

3. And in regards to proper heating solutions, you've already explained 95% of the problem.

4. Many Kiwis have this crazy obsession that to keep a healthy home, you need to constantly open up windows and doors far and wide and endlessly subject your house to the elements. So if you go into plenty of NZ houses during the summer, they will be unbearably hot; in winter, you get mini hurricanes blowing at you indoors. There are scores of people who will spend hundreds of thousands to millions on a house but will cheap out on heat pumps, proper rangehoods, and/or not replace broken extraction fans.

5. People only turn on heating or cooling when things become unbearable, which is energy inefficient. The moment things are warm/cold enough, they instantly switch off the device.

6. If you want to live in these character villas and what have you and stay comfortable/healthy, you have got to be prepared to pay/

I genuinely feel for people without the means to afford properly insulated and constructed homes. But much of the indoor temperature/condensation issues suffered by middle class and up people of NZ are self-induced.

timmmay

20858 posts

Uber Geek
+1 received by user: 5350

Trusted

Lifetime subscriber

#2478372 7-May-2020 07:56

Froglotion:

Doesn't matter how much you heat a house, it doesn't solve the condensation problem.

I'll give you an example.

My first place (built it 2007, so doubled glazed, fully insulated, sealed box), put in one heatpump (small house but also couldn't afford two). Used to get bad condensation in master bedroom as had ensuite. So two showers per night, plus all of the moisture from just sleeping equaled bad condensation. Thought i'd get a heatpump for the bedrooms. They got a lot warmer, but condensation problem was the same. Hmmm. Spoke to someone who designs HVAC on a huge scale. They said on a budget, positive pressure ventilation would solve the problem, but would introduce cold air in winter. Installed a "Drymatic" basic system, condensation was gone in days, maybe 1% of previous condensation left. The difference was night and day, the house dried right out. The only thing I had to changed was put the heatpump on timer to come on in the morning. I didn't care if it was cold after I went to bed. So spent a bit more on heating, but never had condensation again. A good budget result.

So in short, you had no ventilation, you added ventilation, and condensation went away? This is a fairly standard story.

As I mentioned above, in my experience ventilation doesn't have to run 24/7 in a double glazed house. Run it a few hours a day at least to reduce the humidity / moisture and condensation goes away.

With single glazing I think running ventilation 24/7 and making the house cold is the only "solution".

Froglotion

208 posts

Master Geek
+1 received by user: 78

#2478452 7-May-2020 09:36

Natural ventilation was limited in winter yes, but not in summer, hard to keep a house warm with windows open in winter. The positive pressure ceiling vent was located in the middle of the house and pushed air throughout the whole house so removed the need to open windows at all. House location is key too though, in warmer locations having windows open wouldn't be so bad. No one size fits all solution.

Oh and the basic ventilation system I had just ran 24/7 standard. Since most of our moisture was created in the evening, with it not running during that time I feel like the condensation problem will have remained. That was probably the most important time to have it running.

MikeAqua

8024 posts

Uber Geek
+1 received by user: 3817

#2478540 7-May-2020 12:42

The glory of Heat Exchanging ventilation systems is that they transfer heat from the outgoing to the incoming air. This achieves ventilation while limiting heat loss. Dryer air is easier to heat.

Our experience was that we were able to run the heat pump a couple of degrees cooler. I attribute this to two things: -

- Dryer air feels warmer;

- Particular rooms in the house that were very warm during sunny days (Nelson). The system was set up to push air from these rooms through the rest of the house. This meant the whole house was being heated most days in winter. Furniture and surfaces were kept at background level of warmth. This makes a huge difference.

Our power bills decreased and we were more comfortable. We didn't realise how much moisture is held in fabrics with in a home, until we got rid of it (takes a couple of weeks to disappear).

Mike

1 | 2