A crew of only four roofers showed up around 8:00 am this morning. I did not follow their progress closely through the day, but without doubt, these guys put in a full days work. They did not depart until about 8:00 pm.
I did not see Bret (roofing supervisor). He told me yesterday he would be out to see the leak in the roof. I called him around mid-morning. He said he had been there, but did not stop to chat. He said he would call his foreman on site and have him get with me so I could show him where the leak was. The foreman did indeed come around in the afternoon. When talking with Bret, I asked when he thought they would be finishing. He said if it did not rain on Friday (90% chance of 1+ inches of rain is forecast), they will finish by the end of the day Friday. If it does rain, they will finish Saturday. I confirmed with Bret that they were going to install ridge vents on both the main house and the garage. I also asked him to ensure that the gutters and downspouts were clear when they were finished. Finally, I asked him if he knew that the plan was to install active cupolas on both the sunroom and the garage? While he did not say he was aware, he said that was not going to be a problem. I told him that we have not yet ordered the cupolas and it may be several weeks before they arrive. Again he said that was no problem and to just let him know when we wanted them installed. My main reason for asking about the cupolas was to verify with Bret that these can be installed after the roofing is complete, as "Our" Mike has been telling us. According to Bret, apparently so.
I got a return call from Hot Spring regarding the amount of ventilation they recommend. The same lady I talked with yesterday said that she had talked with their engineering group and confirmed there were no quantitative guidelines on how much ventilation was needed.
I called Tyler (architect) to lay out for him my plan regarding the ventilation. I got his explicit approval and then called Frank (HVAC). I talked to Frank's wife who said he would call me back. Around 6:00 pm, his wife (I cannot remember her name, but she was very nice) called again and suggested Frank come out to visit us between 7:00 am and 7:30 am tomorrow. I quickly agreed. I had already put together an email to send to Frank on the assumption that we were going to have talked on the phone and he was willing to accept my proposed path forward.
This the message I intend to give to Frank,
Frank, I want to drive the sunroom ventilation issue to a conclusion so that we can get our cupola order placed. The main questions are: how much fan capacity do we need; where should the fan be mounted; how and from where do we provide makeup air to the sunroom to achieve the desired air flow patterns and avoid negative room pressure when the fan is running.
I have received numerous opinions as to how much ventilation we need, ranging from 0 to 20 air turnovers per hour. I am not taking the zero capacity seriously. So far, the hot tub manufacturer (Hot Spring) has only said that we need "a lot". Unless we get yet more expert opinions, the consensus seems to be that the more flexibility we have, the better chance we will have to being correct. That being said, I am proposing that we start with a middle-capacity fan, with good turn down ability, mounted in the cupola. If we need more than this, we can look into adding an additional fan external to the cupola on the north-facing roof.
I am attaching a brochure of the Xpelair roof fan I found recommended on-line as well as the dimensional drawings of the sunroom (30") and garage (48") cupolas. I do not know if you are familiar with the Xpelair product line. It is a UK company with Coastal Products, Inc. (Seattle) being their US distributor.
Although expensive, the Xpelair RX12 fan seems to have all of the attributes we are looking for in the sunroom exhaust fan. However, if you can suggest another fan that would have similar or superior characteristics, and at a better installed cost, we would appreciate your recommendations. From what I was able to describe verbally to the Xpelair distributor, he said that, while their product has been used successfully in our type of application, we might want to consider just an ACME exhaust fan. This was what Tyler had originally envisioned. I believe you had previously mentioned you like the Broan line of fans. I am estimating the cost of the Xpelair RX12 would be around $1,500 (FOB Seattle). They said there was a 25% contractor discount and it is a stock item.
Here are the attributes of our ideal sunroom fan. Nothing is cast in stone however, knowing that sometimes you may want to make compromises.
- Capacity around 1,000 cfm
- Roof mount, no duct work inside the room
- Fits beneath (within) the cupola (see dimensional drawings of 30" cupola)
- If the ideal fan will not fit within the 30" cupola, we might consider going up to a 36". Not having the ventilation issue resolved is the only reason we have not yet placed our cupola order.
- Ideally, the fan will be completely contained in the cupola with nothing penetrating through the ceiling into the room. The inlet hole in the pine ceiling boards would be covered with a decorative grating that would conform to the contour of the ceiling ridge peak.
- For a 1,000 cfm fan, the hole in the roof would need to be roughly 500 sq in of inlet net free area. This comes from the formula I found taking the cfm/300x144. This may be overly conservative since the inlet NFA of the Xpelair appears to be only 128 sq in (12 3/4" hole diameter), if I am reading their brochure correctly.
- Very quiet. I would suggest a fan with a rating of less than 4.0 sones. While a little "white" background noise would be acceptable, we don't want people to have to speak louder than normal to be heard.
- Weather proof, i.e., the fan assembly is weather tight in itself. This will give us a double layer of protection against weather infiltration (the cupola being the other layer)
- Ideally a variable speed motor, but at least multiple speeds. The Xpelair is a two speed, but the distributor suggested we consider a variable speed EC motor which has an 80% turn down capability. The Xpelair motor is even reversible (not that I believe that would be an important feature for us)
- Louvered to prevent a back draft or excessive heat loss in cold weather. The Xpelair features what they call an electrothermal shutter cassette. The distributor said this is an automatic louver system that will open shortly after the fan is turned on and close when the fan turns off. And it makes a good seal.
- Construction materials that will not corrode. We don't want rust stains dripping down into our room
- Long lived and durable motor, bearings and construction
- Fan to have remote On/Off/Auto selection (remotely started or stopped either manually or by humidistat and/or thermostat)
We will also need to have provisions for a louvered air intake to the sunroom. Again, the same NFA would be needed as used in the roof opening. This louver intake would be automatically opened and closed when the fan is started and stopped. Ideally, the location of the intake louver would not be susceptible to short circuiting and instead create an air flow patter from the bay area (hot tub) toward the exhaust fan.
The fan for the garage is not as demanding since we are not attempting to achieve any asthetics, just ventilation. For the garage application, I would like to have a multispeed fan capable of a maximum capacity of 6,000 cfm. Noise is not a significant issue in the garage. And while the fan does not need to be contained completely within the cupola, we would want the air moved by the fan to be directed to exhaust through the cupola.
We will see how Frank responds tomorrow morning.
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