Location of Wood Pellet Boiler

BigGeorge

Am doing a low energy new build & am looking for advice on the location of the wood pellet boiler. I have a large enough utilitly / plant room for a unit about 1mx 1m with some bulk storage. However, am a bit nervous concerning fire of having the unit operating 24/7 at times with such a large fuel supply in a negatively pressurised room due to the MHRV.

What are the pro / cons of installing the boiler in a garage or is the fire concern real?

BG

Evergreen

BigGeorge wrote: »

Am doing a low energy new build & am looking for advice on the location of the wood pellet boiler. I have a large enough utilitly / plant room for a unit about 1mx 1m with some bulk storage. However, am a bit nervous concerning fire of having the unit operating 24/7 at times with such a large fuel supply in a negatively pressurised room due to the MHRV.

What are the pro / cons of installing the boiler in a garage or is the fire concern real?

BG

The largest advantcage of having a pellet boiler installed in your house is that any heat loss from the boiler is lost into the house rather than the garage, thereby increasing the overall heating efficiency of the boiler. However, if you are going to install a boiler in your house you need to consider a number of things.

1. Does the boiler have a good safety record? Investigate the way the boiler is deisgned to prevent burnback in the boiler, for example, anythinig that uses the plastic drop pipe should be installed inj the garage.

2. Cleanliness. You don't want a system in your house that has to be dismantled and cleaned every week/couple of weeks. Look for a system that cleans itself on a regular basis and taking ash out is a simple and clean process.

3. Size. As mentioned you have a very limited space, possibly enough for a boiler but probably not for a pellet store. Some boilers require a small hopper that feeds the boiler through an auger and they can end up taking over a large foot print. There are plenty of boilers on the market that utilise vacuum feed systems for filling the boiler from the main store. Most systems will allow the boiler and hopper to be between 20 and 30 meters apart. Becuase vacuum hoses are used the route can be flexible, i.e. buried underground, run through the attic, etc.

BigGeorge wrote: »

What are the pro / cons of installing the boiler in a garage or is the fire concern real?

BG

The advantages to installing the boiler in the garage are as follows
1. All boiler system located in the same area
2. Leaves extra storage space in the main house
3. Dust and dirt issues stay in the garage


disadvantages
1. Heat loss goes to the garage not main house
2. Heat lost to ground on way to house
2. You have to go to garage to check the boiler

The fire concern is real in some boilers and not real in others, there are different types of pellet boilers on the market, as follows

Converted Oil Boilers
This is effectively an oil boiler heat exchanger body with a pellet burner head bolted to the front instead of an oil boiler. These systems are very common in Sweden where people don't replace the boiler when installing a pellet system, they just replace the burner head. The problem with these systems is that the use a plastic drop pipe for burnback protection, the way it works is that burnback melts the plastic pipe and then the pellet feed to the burner head is cut off. These systems can run very reliably when installed correctly, however, any cutting corners on chimney design and type can lead to more burnback problems than should be expected - a properly fitted chimney will have no burnback problems. Efficiency of these types of boilers tends to be quite low

Hand fed constant burners
These type of pellet boilers are very common in Denmark, it tends to have a cast iron heat exchanger with a small pellet hopper on the side of the boiler. There is no auto ignition, once the boiler is lighting it stays lighting - when the heating is off in the house the boiler is able to tick over on about 50gms of pellets an hour to keep the fire smouldering. The efficiency of these boilers tends to be higher than the converted oil boiler type, however a lot of them have very poor burnback protection. The feed system on these types of boilers tend to be horizontal augers feeding directly from the hopper to the fire chamber with no fire break. Burnback is prevented from happening by making sure that the hopper lid is always closed. Most of these systems come fitted with built in fire extinguishers, the sales person will try and tell you this is an added featyre - don't be fooled, the only reason these boilers are fitted with such devices is becuase TUV in Germany have said that they are not safe enough for fitting to house in Germany and can only be sold if this device is fitted.

Purpose built pellet boilers
There are many examples of these on the market, mainly manufactured in Austria or Germany - i.e. ETA, Froling, KWB, Paradigma, Okofen, etc.

Burn back is prevented on most of these boilers by forcing the pellets through a fireblock on the way to the fire chamber. The most common way of doing this is using a rotary valve. A rotary valve is basically an enclosed wheel with cells in it (like a miniture version of a water wheel). An auger feeds pellets in at the top of the RV, as it turns it takes a scoop of pellets and then drops the pellets out the bottom into another auger that feeds pellets into the fire chamber. This is the safest form of burnback protection on the market, most boilers that use this system have never had any incidence of burnback in their pellet boilers.

These boilers tend to be the most efficeint on the market with high levels of control built into it, biggest down fall with these boilers is that they tend to be on the expensive side.

Hope this helps?

No6

BigGeorge wrote: »

Am doing a low energy new build & am looking for advice on the location of the wood pellet boiler. I have a large enough utilitly / plant room for a unit about 1mx 1m with some bulk storage. However, am a bit nervous concerning fire of having the unit operating 24/7 at times with such a large fuel supply in a negatively pressurised room due to the MHRV.

What are the pro / cons of installing the boiler in a garage or is the fire concern real?

BG

George

As a wood pellet user and housing designer my experience with wood pellets is to avoid complicated pellet delivery systems, vaccum's, augurs etc because these are the elements that always break down first!! I am cuurrently suggesting to my clients who want to have wood pellets to incorporate a large enough garage for the pellet store to be located above the smaller bolier hopper so in the event of auguer or vacum faliure they can be delivered by gravity!! I also strongly reccomend that you keep your pellets indoors. If you keep the pipe run from the boiler to the house relatively short and have the pipes very well insulated you shouldn't have a huge problem with heat loss.

MicktheMan

Hi George,
if you are doing a low energy new build, would a good wood pellet stove not do the trick for you. You can always have your bulk storage in the garage and feed the stove hopper from this manually when needed. There are some very elegant models on the market and afaik they also work with an external air supply (important if hrv being installed). Just a thought. Mick

homewardbound11

Hi Biggeorge,

I considered putting this in the house also but when you do the calculations of space required for a minimum of 3tonne of bulk delivery 1m by 1m would not cover the space required. You'd be closer to 2 by 2 to get near to this.
Also the auger lenght and free space around the burner to comply with manufacturers spec or regulations. You will find also that most recommend a seperating wall wither it is non combustable material or not. Also on a fire issue there will be grounding requirments to avoid electrostatic spark occuring during fills. This would as normal happen regardless of it being internal or not.
Lastly too am using HRV and to get around the issue of room selaing i changed the design at the time to have these two rooms closed off to the rest of the house and have 2 vented doors externally. One to access the boiler room and one to access the bulk storage.

Aven after researching all of this and loosing nearly 6m2 of space in total i decided against all of it on cost basis. The prices will come down further on pellets or at least untill oil starts to rise again.
I am building a garage that will eventually house all of these components with a fire risk reduced to the garage only.
Best of luck to you.
Pat

BigGeorge

Thanks for all the recommendations & advice. I need to do some more research on particular brands & their trackrecord.

I did look at the stove option, but these deliver a lot of their heat into the room rather than into the back boiler where I need it to go. Secondly, I've seen a house where there is one in the living room, and the walls etc.. have a very fine layer of wood dust on them. On that basis was looking for a boiler rather than a stove, to be located in a plant / utility room. There are a number of models than have 100-200kg of storage built in which would mean filling the mini hopper every few weeks.

Looking at the fire / smoke damage potential, I've been looking at putting the boiler, with whatever pellet storage, in the garage, but believe this have implications for the BER & PHPP.

SDW

The National Fire Safety Code at NFPA 211 sec 12.2.4 says:

"Solid fuel burning appliances shal NOT be installed iny any garage."
It is amazing how many plumbers, HVAC retailers, etc either ignore or don'y know this but you can bet your insurance company excludes coverage for code violations.

galwaytt

SDW wrote: »

The National Fire Safety Code at NFPA 211 sec 12.2.4 says:

"Solid fuel burning appliances shal NOT be installed iny any garage."
It is amazing how many plumbers, HVAC retailers, etc either ignore or don'y know this but you can bet your insurance company excludes coverage for code violations.

..'code'..?...that sounds like US-speak ?

I think the issue there is the combination of open flame/hot surfaces and exposure to combustible gases from parked cars (petrol etc etc).

...around here a 'garage' is a place for the boiler........and the bicycle's.

Mind you.......it usually has a lawnmower as well...........hmmmmm