I have four smoke/CO detectors in my home. One in each bedroom and one in the hallway immediately outside of each bedroom.

Monday morning at midnight, the one outside my bedroom started the "after 7 years initiate self-destruct" beep, waking me from a dead sleep. I roused my son and made him drag out the big ladder to disconnect it.

I took a pic of the model number on the unit and ordered new ones on Amazon. I ordered a three-pack since I have multiple smoke detectors (intending to go back and purchase a fourth, as needed).

Monday night, the one outside of his bedroom started beeping (thankfully at the more reasonable hour of 7 pm). That ceiling is slightly lower, so I was able to remove it using a step-ladder. It's the same model as the one we disconnected the previous night.

We decided that it was only a matter of time before the units in the bedrooms failed, too, so he got up on the ladder again and took down the one in my bedroom. As soon as he took it down, he realized it's a different model than the ones in the hallways. A check of the detector in his bedroom revealed it's the same model as the one in my bedroom, but different than the ones in the hallway.

I, of course, expected that they would all be the same when I bought the replacements on Monday morning. Even though they are all by the same manufacturer (Kidde), the ones in the bedroom are a different size, so the replacement units I purchased won't fit on the bases that are installed in the ceilings of the bedrooms.

I can buy replacements for the other model, but why in the heck are they different? What is the point of installing two different types of smoke detectors? Is there some reason why the ones in the bedroom are different than the ones in the hallway? According to the Kidde website, both models are ionization detectors.

I'm pretty sure smoke detectors are just a big practical joke by someone. They are nothing but a pain in the ass.

Does the hallway one also include carbon monoxide?

Could have been a later addition as well.

I replaced all of my bedroom sensors with hard wired units with a battery backup (to meet code during window install) and then added a couple of Nest Protect sensors for remote monitoring.

Could just be that someone replace some and not the others or added new ones.

They should come with mounting plates and pigtails to swap to whatever model you bought.

House was purchased as a new build, so all of the detectors are original to the house. The ones in the hallways (immediately outside the bedrooms) are CO/smoke. I think the ones in the bedroom are smoke only.

Both models are hard wired.

It's possible that some of your smoke detectors are AC power hardwired to the house, and others are low voltage DC power connected to your security system.

DeLaHonta said:

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It's possible that some of your smoke detectors are AC power hardwired to the house, and others are low voltage DC power connected to your security system.

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I don't ~think~ that's the case because when I moved in, I had ADT set up my security system. They couldn't use any of the existing detectors, so I actually have a THIRD set that they installed. I suppose it is possible, though.

Eh, I wouldn't fret about it. Buy the ones you want and swap them out.

03_Aggie said:

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Eh, I wouldn't fret about it. Buy the ones you want and swap them out.

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I was mainly just curious if there was a valid reason for there to be two different kinds installed - other than the builder was lazy and just installed whatever they had on hand.

I'm inclined to agree with Vernada that this is all some sort of practical joke.

I am admittedly not a code guru, but I think you are required to have a CO2 detector within 6ft or so of a gas furnace. Do you have one or more of those in your house?

Yes, my heater is gas. It's up in the attic, but the air intake is near one of the CO/smoke detectors.

I'm assuming it's code to also have a smoke detector inside the bedroom (even though the units inside the bedrooms and outside the bedrooms are no more than three steps apart). I just wish they'd installed all the same model. I suppose the ones without the CO detector were cheaper.

You must have a smoke detector in every bedroom. You must also have a CO detector on every level of the home and in a central area to bedrooms. So the builder followed code by putting smoke detectors in the bedrooms and a smoke/co detector in the hallway. You can use smoke/co everywhere, but they are more expensive.

GrimesCoAg95 said:

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You must have a smoke detector in every bedroom. You must also have a CO detector on every level of the home and in a central area to bedrooms. So the builder followed code by putting smoke detectors in the bedrooms and a smoke/co detector in the hallway. You can use smoke/co everywhere, but they are more expensive.

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They would be cheaper if the manufacturer would take out the module that ensures they always run out of battery at 1 am.

Ulrich said:

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GrimesCoAg95 said:

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You must have a smoke detector in every bedroom. You must also have a CO detector on every level of the home and in a central area to bedrooms. So the builder followed code by putting smoke detectors in the bedrooms and a smoke/co detector in the hallway. You can use smoke/co everywhere, but they are more expensive.

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They would be cheaper if the manufacturer would take out the module that ensures they always run out of battery at 1 am.

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Oh, the ones with the CO sensors are even worse. They "expire" after 7-10 years, which means that changing the battery isn't the fix (mine are hardwired anyway).

You have to replace the entire unit. So, when mine started beeping (every 30 seconds) at midnight, the only option was to disconnect it from the power source (which thankfully doesn't cause it to go into full alarm mode).

I can't believe how many times I typed CO2 instead of CO in my posts. And I know better.

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Monday morning at midnight ...I roused my son and made him drag out the big ladder to disconnect it.

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I wonder how many people have died trying to disable a smoke detectors on ladders in the middle of the night?

sleepybeagle said:

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Quote:

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Monday morning at midnight ...I roused my son and made him drag out the big ladder to disconnect it.

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I wonder how many people have died trying to disable a smoke detectors on ladders in the middle of the night?

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Or how many angry teenagers have contemplated assaulting their parents after being awakened in the middle of the night to disable a smoke detector.

Vernada said:

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I'm pretty sure smoke detectors are just a big practical joke by someone. They are nothing but a pain in the ass.

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I have an extended family member who died as a teenager because he couldn't get out of a fire in his apartment. All the smoke detectors were out of batteries.

Ideally your CO detectors should be about five feet off the ground on a wall and your smoke detectors on a ceiling away from HVAC vents. As someone else mentioned, they could be battery powered, hard wired to 120V, or connected to the security system (Wired or wireless). If they're just simple battery units that are not part of the security system pick up the 10 year lithium ion units. Get separate CO2 monitors and mount them at five feet on a wall in the areas close to gas sources but at least 15 feet away.

Note that wired units whether 120V or security should be wired in series, so if one goes off, all in that zone will go off.

I prefer to have both 120v or lithium battery and security sensors for redundancy and remote notification.

DeLaHonta said:

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It's possible that some of your smoke detectors are AC power hardwired to the house, and others are low voltage DC power connected to your security system.

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Not to hijack, but where do y'all think is the best place to find the low voltage DC smoke detectors that connect to security system? The little that I have looked online they seem to be real expensive. I have 8 of them in my house.

I buy from alarmsystemstore.com, Amazon, or eBay. eBay is the cheapest for alarm system parts in my experience, but customer service is obviously minimal. I use GEOARM for self monitoring, but I wouldn't recommend buying parts from them unless you don't mind waiting a couple of months for delivery. Their monitoring customer service is great though and very reasonably priced.

TXTransplant said:

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I just wish they'd installed all the same model. I suppose the ones without the CO detector were cheaper.

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That wouldn't meet code requirements,... You need some CO detectors...

This really sounds like a whole bunch of fretting about nothing.

TMoney2007 said:

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TXTransplant said:

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I just wish they'd installed all the same model. I suppose the ones without the CO detector were cheaper.

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That wouldn't meet code requirements,... You need some CO detectors...

This really sounds like a whole bunch of fretting about nothing.

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Yes, I know I need CO monitors. But they could have installed four CO/smoke detectors, instead of two with CO and two without.

It's just a PITA. Especially when they malfunction in the middle of the night, you have 14 ft ceilings, and can't drag out the big ladder to reach said ceilings because you just had surgery a few weeks ago.

At least with Honeywell systems the dual detectors are more expensive and require an additional module outside of the panel. Basically they increase the complexity. I prefer to use separate detectors and zone expanders if needed. It also allows for proper placement of different kinds of detectors.

TXTransplant said:

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TMoney2007 said:

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TXTransplant said:

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I just wish they'd installed all the same model. I suppose the ones without the CO detector were cheaper.

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That wouldn't meet code requirements,... You need some CO detectors...

This really sounds like a whole bunch of fretting about nothing.

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Yes, I know I need CO monitors. But they could have installed four CO/smoke detectors, instead of two with CO and two without.

It's just a PITA. Especially when they malfunction in the middle of the night, you have 14 ft ceilings, and can't drag out the big ladder to reach said ceilings because you just had surgery a few weeks ago.

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For the once every 7-10 years that you have to touch them, I suppose it is terribly burdensome...

aggieforester05 said:

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At least with Honeywell systems the dual detectors are more expensive and require an additional module outside of the panel. Basically they increase the complexity. I prefer to use separate detectors and zone expanders if needed. It also allows for proper placement of different kinds of detectors.

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Mine aren't anything fancy - just Kidde brand. But when I looked up the models to purchase replacements, there is a cost differential between the two types that are installed in my house. When you're building 100s of houses at the same time (as my builder was), it probably adds up.

That's a valid point about placement, though. CO monitors should be placed closer to the ground, but mine are installed in 14 ft ceilings.

TMoney2007 said:

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TXTransplant said:

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TMoney2007 said:

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TXTransplant said:

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I just wish they'd installed all the same model. I suppose the ones without the CO detector were cheaper.

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That wouldn't meet code requirements,... You need some CO detectors...

This really sounds like a whole bunch of fretting about nothing.

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Yes, I know I need CO monitors. But they could have installed four CO/smoke detectors, instead of two with CO and two without.

It's just a PITA. Especially when they malfunction in the middle of the night, you have 14 ft ceilings, and can't drag out the big ladder to reach said ceilings because you just had surgery a few weeks ago.

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For the once every 7-10 years that you have to touch them, I suppose it is terribly burdensome...

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Well, if I'm going to go to the trouble and expense of replacing them all, I would like to be sure I'm replacing with the appropriate units (and not simply assume the builder made the best/safest choices). But apparently you just skipped over that part of the discussion.

TXTransplant said:

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TMoney2007 said:

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TXTransplant said:

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I just wish they'd installed all the same model. I suppose the ones without the CO detector were cheaper.

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That wouldn't meet code requirements,... You need some CO detectors...

This really sounds like a whole bunch of fretting about nothing.

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Yes, I know I need CO monitors. But they could have installed four CO/smoke detectors, instead of two with CO and two without.

It's just a PITA. Especially when they malfunction in the middle of the night, you have 14 ft ceilings, and can't drag out the big ladder to reach said ceilings because you just had surgery a few weeks ago.

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Your builder isn't going to go above and beyond code unless you ask him to. If this is cookie cutter home, then no way.

They put in min. amount of co/smoke detectors ($$$$) and the remainder where required are only smoke ($)

TXTransplant said:

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(even though the units inside the bedrooms and outside the bedrooms are no more than three steps apart).

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If you close your or your child's door at night, do you want the detector in the hallway outside the closed door to be the one to let you know there is a fire in the bedroom? Or vice versa.

And on that note...

From a fire safety standpoint you should be closing doors at night. On the other hand it's hell on the HVAC.

Then there's the difference between photovoltaic and ionizing units.

62strat said:

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TXTransplant said:

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(even though the units inside the bedrooms and outside the bedrooms are no more than three steps apart).

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If you close your or your child's door at night, do you want the detector in the hallway outside the closed door to be the one to let you know there is a fire in the bedroom? Or vice versa.

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I understand why there are smoke detectors in the bedrooms. I'm not sure why the CO/smoke detectors are immediately outside the bedroom doors. Especially when one is right near my A/C intake and both are 14 ft off the ground (which I have learned is not appropriate for CO detection).

Also, now that I'm really thinking about this, I'm wondering why these units are the only ones the builder installed. There is nothing in or near the office/third bedroom, the laundry room, or my bedroom-sized walk-in closet.

I did have detectors installed in the attic and garage when ADT came to set up the alarm system.

TXTransplant said:

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62strat said:

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TXTransplant said:

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(even though the units inside the bedrooms and outside the bedrooms are no more than three steps apart).

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If you close your or your child's door at night, do you want the detector in the hallway outside the closed door to be the one to let you know there is a fire in the bedroom? Or vice versa.

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I understand why there are smoke detectors in the bedrooms. I'm not sure why the CO/smoke detectors are immediately outside the bedroom doors.

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Same reason why they are immediately inside the bedroom door; Most people have closed doors at night, and with a closed door, only one detector (in or out) is not sufficient for smoke, which could be on either side of the door. Fires do not only start in bedrooms. If your hallway is on fire (which is your way out of the bedroom and house), a sleeping person needs to be alerted so they can get out before it's too late. If we didn't have bedroom doors, we wouldn't have one right inside and outside the bedroom.


Your closet doesn't need one, because you don't sleep in there,and you don't have to exit through there to get out of house. When that closet fire smoke makes its way to the bedroom, then your bedroom alarm goes off and you can get out.

Your office should only have one assuming the office has a closet, which technically means it is a bedroom. Without a closet, it's not a bedroom, so code doesn't require it. Our front room/office/dining room doesn't have one because there is no closet.

Everything you said makes sense from a code perspective, but it doesn't seem to be the best arrangement for my house, which has an unusual layout.

My house is about two rooms wide and four rooms deep. The two bedrooms (and the existing detectors) are on the far NE and SW corners of the house. If a fire started in the center of the house (where the laundry, closet, and office are), the smoke would have to travel to outside of the bedrooms at those corners of the house to set off the alarms.

My closet is actually another point of exit for the master (if there were a fire outside the master bedroom door, I could get out through the bathroom and closet, which connects to the laundry room/front hallway).

If fire/smoke from the center of the house travels to the detector right outside the secondary/front bedroom, it actually could block the point of exit from that bedroom (you could still go out a window).

Based on what you've said about code, I understand why the detectors are positioned where they are. But having one in the center of the house makes sense, too, in order to trigger an alarm before the fire/smoke spreads to the bedrooms.

I never paid much attention until now, and I may look into have another one installed to cover the office/laundry room area in the center of the house.