Pellet burner installation advice needed please - concerning issues

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Sep 19, 2017
Hello everyone, it's my first time posting here so I'll start by saying hi... "Hi" :)
I apologise in advance, this is a long post as I have a few different questions and worries, therefore I want to explain in detail as I'm quite concerned.

Situation and my concerns:
My elderly father has recently bought 2 pellet burners to replace his old and expensive to run log/coal stoves. He bought them with the intention of just straight swapping them, putting the new pellet burners in the same places the old log stoves were as he assumed they worked and vented the same way. But, I knew they have some differences compared to conventional log stoves, so I started doing some research. Upon doing so I immediately realised he might have some issues and potentially dangerous ones, which is why I'm here.
Plus, to add to the issue, the pellet burners he bought, although a reputable brand (apparently) and brand new from a store, they came with Zero information or instructions, just a generic print off piece of paper saying; don't get water on them, only burn pellets, don't open the door while burning... that sort of thing. So he knows nothing about how to install these burners or their requirements to work properly.

So, my father's home has 2 separate brick chimneys on either side of the house. He's installing the two pellet burners in the same places the old log/coal stoves were and venting them into the chimneys in the same way. He's trying to save as much money as possible because of his pension, so instead of buying the solid steel pipes that the store recommended, he went to another store and bought some steel flexible pipe, called (INOX AISI Steel) whatever that means.
He intends to simply use a piece of this flexible pipe attached to the exhaust on the burner, then bend it 90degrees up, straight for roughly 50-60cm, then a 90degree bend and attach it to a pipe connector cemented in the wall of the chimney.
My concern is, I can only find one or two posts online from people using this flexible pipe as an exhaust, every uses this flexy pipe as air intake but not as exhaust, plus 99% of posts I've read people recommend you use solid steel pipes. I'm worried that if this flex pipe gets damaged with a small tear or hole, it will blow toxic gases into the house. Or, I know it's a type of steel, but as it's very thin would the heat be an issue causing the pipe to get soft or brittle.

One more thing I discovered, was that some pellet burners require an external air intake, which I'm pretty sure these ones require as they have 2 pipe connections sticking out the back of the machine.
But when I told my father it means a second pipe needs to go through the wall to suck air in, he just shook his head and said; "Don't be silly, it will be fine".
I love my father very much, but no matter how old I am he will always see me as a little girl and therefore he assumes he knows best and he knows how to do everything better. I tried explaining what I had read, that without an external air intake the burner would suck in lots of air from inside the house and cause negative pressure, which causes a slight vacuum and can result in gases being released into the house... but again, he just shook his head and said; "it will be fine."

My questions:
So, I guess my first question is regarding the pipes - Is steel flexible pipe safe to use, to connect the exhaust to the chimney, or does it have to be solid steel or double layers pipes??

Next thing - is exhausting directly into a traditional brick chimney OK to do? The internal dimensions of the chimney are roughly 25cm x 25cm if that matters.

Regarding an external air intake, is this an absolute must regardless of the size of the house or burner? Is it dangerous to not have one?

Lastly, for now at least, I read that you need a UPS (battery backup) if you live in an area prone to power outages. Well, my father lives in an extremely rural area and subsequently he gets dozens, sometimes hundreds of power outages every year, some only last 2 minutes, but last winter he lost power around 30 times, a few occasions for 4-5 days straight.
Therefore, would a UPS be needed for safety, not just so he doesn't lose heating, but so the burners don't explode or blowout gases and smoke if the power goes off during the night or while he's out??

Thank you to anyone that reads through this, I appreciate it's a bit of a wall of text, but I'm really concerned about him, he always thinks he knows best and it will be fine don't worry, but he regularly gets things wrong, he just doesn't admit it.
Really appreciate any help and advice, especially any links to helpful installation tutorials.

Thanks again,
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Most stove manufacturers have PDF install and operation instructions at their web sites that you can down load. He needs to do the install according to the manufacture instructions. generally speaking any vent pipe inside the house needs to be double wall pellet rated venting and seal the joints as well. Again, generally speaking it's pretty safe to go up an existing wood fire rated masonry chimney, even if against the install instructions but some stoves require lesser diameter liners to be installed. Generally if that is the case a 4" liner is the common size used. But we have plenty of members here who have gone directly into masonry chimneys once past the double wall pipe hook up to the stove. But really it's all about those instructions.

Some stoves just won't run correctly without the outside air kit hook up. Again if it's required in the instructions this is probably the case. Otherwise it's an option that just reduces drafty conditions in the house. But several brands especially when installed in really tight new construction houses just simply require the out side air kit period.

With enough vertical rise ( as with a masonry chimney) you generally won't need the backup power supply. The natural draft of the chimney would cover that.

Get back to us with the actual brand name of the stove and we might be able to help a bit more. Best of luck with your dear dad meanwhile, Sophie ! Also,I don't know the rules in Europe compared with the US.
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For power outages a UPS will run the stove for a short time .
If extended outages you will need a generator and fuel to
run it and keep warm . An OAK (outside air kit) is necessary in a
tight house (or open a window) if the house isn't tight an OAK
is not necessary but helps with drafts in an old house .
If you give us the name of the stove we can tell you more .
Welcome to the forum and good luck with your Dad
Hi, sorry for the delayed reply, things have been crazy here this week.

Thank you both for your advice, I really appreciate it.
I had a good search around the web for a manual for these burners but I can't find anything. The make is: Punto Fuoco and the model is: Susy. Manufactures site: Here

Regarding a few things you mentioned - his house is fair large and open, so hopefully it will be OK without an air intake as they ain't close to an exterior wall and my father has made it clear he is not putting a 12+ meter pipe up the chimney and have it sticking out the top to suck in fresh air.

As he lives in an area that suffers from constant power outages he does already have a large generator plus a large fuel store, so he's OK with regards keeping the house warm, but obviously that needs to be switched on, I'm worried about a power outage in the night or while he is out. I think I'm going to use his smoke and CO detectors, place them close to the burners and try switching the power off when the fires are full and burning at maximum rate, then see if any smoke is released into the house and use the detectors to check for CO.

Lastly, my main concern still is this flexible pipe he wants to use. It is steel so it's fairly strong and rigid, but it's still flexible and therefore much thinner and fragile than solid steel pipes, plus only single walled. He point blank refuses to buy the solid double walled pipes as he thinks they ain't needed, but also because the price of them here is insane, near €100 ($120) for a 1m (3 foot) straight and bends are just as expensive, he worked out it would cost him as much as one of the burner cost! So I do get his reluctance, he doesn't have the money and nor do I, but safety is more important.

Have you ever heard or seen anyone using this type of flexible pipe as an exhaust?? Would you say it's unsafe??
I have corrugated stainless pipe that lines my masonry chimney ( made for pellet and or wood stove installation in an unlined or oversized lined chimney), it protrudes into my fireplace below a block off about 18" or so and is hooked to a proper connector and sealed with red rtv. From there down I have the various adapters and correct pellet pipe in place, but it wouldn't pass insurance inspection with out that anyway. Stainless corrugated pipe can handle the heat, that isn't the issue, it's the heat and combustibles around the pipe, not to mention sealing it off at the joints ( but that is true of any joint). I can't advocate an incorrect install but that isn't to say it won't work LOL.

FWIW, if I open the door on my stove to scrape the burn pot and let a little smoke and gasses into the house it's never set off a smoke or CO detector yet but stinks up the living room pretty well if I dottle.. But a frying pan in the kitchen has many times. Also I have a clean out t in my venting to the stove, the cap used to leak on start up and you got a faint whiff of smoke in the living room, that never set anything off either. i taped up the seam and that was the end of that issue, which was only in shoulder season anyway.

Pellet venting is under positive pressure, if smoke or gasses can find a place to leak they will. It's not like wood stove venting that is in negative pressure and leaks sucked up the chimney. So the key is sealing all joints. Flex pipe has to be the solid wall type, it can be corrugates so it will bend but it can't be like the automotive flex that is a bunch of loose joints put together or it will leak. But you will probably smell it in the house before ever setting off an alarm. in fact burning off or curing the paint will set off every alarm in the house but a little leak in the venting won't. Least that is my experience.

In the download section of the website you linked are PDFs of typical installs. His stove is probably similar if not the exact model. You could try contacting the company too.
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He intends to simply use a piece of this flexible pipe attached to the exhaust on the burner, then bend it 90degrees up, straight for roughly 50-60cm, then a 90degree bend and attach it to a pipe connector cemented in the wall of the chimney.
Thanks again,

Hello Sophie,

Your dads installation in the masonry chimney has much in common with the one I made in 2008, when I replaced the antigue crown stove ( krone ovn ) that was originally installed in our old family house, when it was built in 1898.

BTW, I still have the old crown stove on the attic in case the Whitfield breaks down for good. See attached picture of the antigue exhaust flue.

But my install was somewhat different and certainly a lot cheaper. Here's how:
The height of the exhaust flue of the antigue coal stove was also much taller than the present Whitfield pellet stove, so I simply closed the hole in the masonry chimney with mortar of this specification: 1 part cement to three parts sand + very little water. A very strong mixture. To save some mortar, I mixed the mortar with some of the brick fragments produced, when I made the other hole below to the "new" pellet stove. You can see the installation on one of the attached pictures. Also, the hardened mortar in the closed hole is visible.
Sophie, your dad must be proud to have such a caring daughter. Please give him the best regards from a cheap Dane and tell him that he is wasting his money on the very long flexible INOX liner with 2x90 Degree bends. Also the draft in the pellet stove will be much better with a direct went into the chimney like the one I have made. See attached picture of my very short flue.
Note: A cleaning lid like the one on my flue is absolutely necessary!
Now, I don't know where in Europe you live, but here's a link to a German webshop with just what your dad needs.
Note the special flange for masonry chimneys. This has a diameter a little bigger than the flue pipe. To make an airtight seal a fibre rope is pressed in between. Perfectly airtight, but still giving flexibility for thermal expansions/contractions. And of course vibrations in the floor.

Regarding an external air intake, is this an absolute must regardless of the size of the house or burner? Is it dangerous to not have one?
Well, our house is very old and pretty leaky around doors and windows, and we don't have any powerful ventilation systems in the kitchen or other rooms, so no problem.
If your dads old stoves have been used until now with no draft issues, then the pellet stove certainly will, too. Even without an out side air kit (OAK).
In my situation it is very difficult to make an outside air supply, since the chimney is placed in the center of the house. Your dads chimneys are placed close to the outer walls, so an OAK set up will be a lot easier. An OAK is not just for safety, it also saves a lot of heat from being wasted.

Pellet burner installation advice needed please - concerning issues Pellet burner installation advice needed please - concerning issues Pellet burner installation advice needed please - concerning issues
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