Smoke detectors, Ionization vs Photoelectric...

[Transition Zone]

On Monday, November 30, 2020 at 7:40:03 AM UTC-5, Frank wrote in alt.home.repair:

On 11/30/2020 5:20 AM, Dean Hoffman wrote:
On 11/29/20 10:07 PM, Sid 03 wrote:
Looking to install some new smoke detectors. I was going to install
Ionization type smoke detectors in the lower floors and then a
combination smoke and CO detector on the 3rd floor where the
bedrooms are located.

I noticed that most of the combo detectors do not use ionization to
detect smoke, but use photoelectric type sensors.
Is this a a big deal or should I stick with the most popular
ionization type ?
Years ago I was told by a contractor to not install combo detectors,
but to keep the CO and Smoke detectors separate ?
Does anyone have an opinion on that ?

If the CO detector has an interconnection wire for other alarms,
should you connect it to the interconnection wire for the fire-Alarms ?
All this stuff is manufactured by Kidde, so I am assuming that is all
compatible ?

Thanks
Sid.

This is what Consumer Reports has to say. They haven\'t tested
them for a couple years.

This is as of June 2018.

Consumer Reports wasn\'t satisfied with any combination
smoke and carbon monoxide detectors they tested then.

These are the dual sensor smoke alarms.
First Alert 3120B $30 Score 91
Kidde P12010 $30 Score 91
First Alert SA320CN $23 Score 87
Kidde P19010 $25 Score 87

Ionization smoke alarms.
First Alert SA9120BCN $25 Score 55
Kidde KN-COSM-1B $35 Score 55 Note 1
Kidde RF-SM-DC $40 Score 53
First Alert SA303 $12 Score 51
First Alert SA304LCN $24 Score 51

Photoelectric smoke alarms
First Alert 7010B $25 Score 55
Nest Protect $129 Score
55 Note 1,2
Nest Protect $129 Score
55 Note 1,2
First Alert SA501CN $60 Score 53 Note 2
First Alert SC051CN $70 Score 53 Note
1,2

1 Combination smoke/carbon-monoxide alarm, also rated as CO alarm.
2 Interconnects wirelessly.

I knew that CO detectors had a finite lifetime, 7-10 years, and now note
that smoke detectors are recommended to be replaced by 10 years. Still
not sure a combo appeals to me since I got over 20 years out of two
smoke detectors before I replaced them.

Its easy to forget and just leave the detector in place.