Solid fuel with a buffer tank

Dr4gul4

I've skirted over the search, and found a few other threads from way back where others have mentioned this style of installation but im still a touch lost in getting an official answer. perhaps somebody here can help .


The overview is as follows, 3500 sq foot house, underfloor on both levels, currently being serviced badly by an oil burner.

I've been investigating the possibility of installing a solid fuel boiler and a 1500 ltrs buffer tank in the garage, and dual piping it to said buffer tank ( all done by a plumber of course)

The crooks of my concern is I'm hoping to install a hopper style system, and use Pea coal say 75% of the time, and where possible manual load logs / wood.

I've been informed by one plumber that these hopper system will not work with a buffer and in such a configuration, and should instead be directly plumbed in to the underfloor pipes.

I will point out however, he's also stated that if I were to forget the hopper version, and use a manual load boiler, I could then pipe all in to a buffer tank ..


Any thoughts on this would be a relief shall we say.

antoinolachtnai

I don't really know much about it, but it sounds like you are doing something expensive and somewhat risky.

What prompts you to move away from oil? Do you have environmental concerns, concerns about security of supply or something else?

I don't understand your plumber's conclusions about buffer tanks, but maybe he has a good reason.

I am particularly intrigued by the suggestion that a solid fuel boiler be plumbed directly to underfloor heating pipework.

I would suggest that you get all the recommendations from the manufacturers of the boiler equipment you want to use and implement the system exactly as they propose. If you are unsure, I would contact the manufacturer for their recommendations.

Ideally, your plumber should be doing this.

Dr4gul4

antoinolachtnai wrote: »

I don't really know much about it, but it sounds like you are doing something expensive and somewhat risky.

What prompts you to move away from oil? Do you have environmental concerns, concerns about security of supply or something else?

I don't understand your plumber's conclusions about buffer tanks, but maybe he has a good reason.

I am particularly intrigued by the suggestion that a solid fuel boiler be plumbed directly to underfloor heating pipework.

I would suggest that you get all the recommendations from the manufacturers of the boiler equipment you want to use and implement the system exactly as they propose. If you are unsure, I would contact the manufacturer for their recommendations.

Ideally, your plumber should be doing this.

Mostly it's driven by the fact the current installation isnt powerful enough to produce heat to the entire house, and the cost associated is close on €3500 a year in oil.

I figure a buffer tank, in any format would ease this, as the Burner ( oil/ solidfuel) would be only ever heating the tank of water beside it.

Wearb

Dr4gul4 wrote: »

Mostly it's driven by the fact the current installation isnt powerful enough to produce heat to the entire house, and the cost associated is close on €3500 a year in oil.

I figure a buffer tank, in any format would ease this, as the Burner ( oil/ solidfuel) would be only ever heating the tank of water beside it.

What BER does the house have? What's the kw output of the oil boiler (or model)?

Dr4gul4

Wearb wrote: »

What BER does the house have? What's the kw output of the oil boiler (or model)?

Original BER was B3, however we've since had the walls pumped and 400 mm or insulation installed in the attic.

The current unit is a Grant 90-120 which based on the manufactures rating is a 26 -36 KW boiler.

Pete67

A buffer tank will not save energy costs simply by being close to the boiler, it may save a little by allowing the boiler to run at a constant load and hence more efficiently. However the piping losses between the house and the buffer tank will be the same as before, and the buffer tank will also loose some heat to the surroundings. But you can only take heat out of the buffer tank that you have already put into to it, so it is not an energy saving device as such.

It should work well with an underfloor heating system, as the buffer tank can be kept at a suitable temp for the underfloor, say 35 degrees, allowing the boiler to stay in condensing mode permanently, which will be more efficient. I see no reason not to use a buffer tank with a hopper fed solid fuel system if it is properly designed, but check with the boiler manufacturer for their recommendations. A modern condensing oil boiler may not be much more expensive to run and will be a lot more convenient.

Dr4gul4

Pete67 wrote: »

A buffer tank will not save energy costs simply by being close to the boiler, it may save a little by allowing the boiler to run at a constant load and hence more efficiently. However the piping losses between the house and the buffer tank will be the same as before, and the buffer tank will also loose some heat to the surroundings. But you can only take heat out of the buffer tank that you have already put into to it, so it is not an energy saving device as such.

It should work well with an underfloor heating system, as the buffer tank can be kept at a suitable temp for the underfloor, say 35 degrees, allowing the boiler to stay in condensing mode permanently, which will be more efficient. I see no reason not to use a buffer tank with a hopper fed solid fuel system if it is properly designed, but check with the boiler manufacturer for their recommendations. A modern condensing oil boiler may not be much more expensive to run and will be a lot more convenient.

I had figured as much my self, the run of pipes will be reviewed and if possible replaced, or reinsulated .

Off to talk to the manufacturer now i guess to find out if what this one plumber is telling me is simply spoof.

Water John

You have to locate as to why the house is using so much oil. As a B3 house it should not require a lot. So no matter what system you put in, the house is using too much energy, why?
You are using something like 5,000ltrs a year.
The BER may be presuming a level of floor insulation, that simply isn't there. That would be my first thought.

Dr4gul4

Water John wrote: »

You have to locate as to why the house is using so much oil. As a B3 house it should not require a lot. So no matter what system you put in, the house is using too much energy, why?
You are using something like 5,000ltrs a year.
The BER may be presuming a level of floor insulation, that simply isn't there. That would be my first thought.

I 'd think it's due to the run of pipes between the down stairs mixer and the actual boiler return and without a doubt in part due to the insulation in the underfloor, ( less than .06 greater than 0.25, or so the ber says )

By investigating the external portion of the pipes, and installing the buffer tank, I hope to reduce the loss in heat while it's traveling across from the garage to the mixers.

But more so, By heating at the buffer tank, I dont really care if i loose 10 degrees on the way over and back, as the cold return back in to the tank will only have a small effect until the boiler kicks in to bring it back up to say 70 degrees again ..

Unless i've my pipes the wrong way around of course.

Water John

The BER doesn't know as the engineer would not have done only a visual inspection. Running a two pipe insulated pipe will help a bit. But if you're heating the worms then no matter what fuel or system, it will eat energy.

Using as cheap a fuel as possible will well pay you in those circumstances.
A timber gasification unit with a large buffer tank may be worth investigating.

Dr4gul4

Water John wrote: »

The BER doesn't know as the engineer would not have done only a visual inspection. Running a two pipe insulated pipe will help a bit. But if you're heating the worms then no matter what fuel or system, it will eat energy.

Using as cheap a fuel as possible will well pay you in those circumstances.
A timber gasification unit with a large buffer tank may be worth investigating.

I'd agree 100% on the visuals only by the ber engineer.

Something from pereko, or defro looks a good option, as i've plenty of dried timber as is, but realistically, I'd like a duo model, pea coal + timber. which brings me back to the original Q of why this plumber is telling me it's not efficient with a buffer tank ..

Maybe the manufacturers will get back to me with some guidance.. it's getting chilly already !

Sam Kade

Dr4gul4 wrote: »

I'd agree 100% on the visuals only by the ber engineer.

Something from pereko, or defro looks a good option, as i've plenty of dried timber as is, but realistically, I'd like a duo model, pea coal + timber. which brings me back to the original Q of why this plumber is telling me it's not efficient with a buffer tank ..

Maybe the manufacturers will get back to me with some guidance.. it's getting chilly already !

I looked into installing a solid fuel boiler last year and went against it in the end after asking people that already had them installed. They are supposed to burn minimal fuel so much so that you can keep them burning 24/7. In reality I am told by people that have them that they use way more fuel and users that had intended to keep them burning all day only use them for 4-5 hours.

antoinolachtnai

Is the garage in a separate building? If it is and you can improve the insulation on the piping, you will certainly solve a lot of problems.

If you are losing 10 degrees on the way over and back, then it doesn't matter whether you have a buffer tank or not, you are losing an awful lot of heat to the environment.

Water John

A wood gasification system is different than wood burning. The buffer tank is over 1,500 litrs. You fire it up a couple of times a week. Most can be filled with split log.
It's limiting your fuel cost, I'm looking at.

Look eg BMK

Dr4gul4

Sam Kade wrote: »

I looked into installing a solid fuel boiler last year and went against it in the end after asking people that already had them installed. They are supposed to burn minimal fuel so much so that you can keep them burning 24/7. In reality I am told by people that have them that they use way more fuel and users that had intended to keep them burning all day only use them for 4-5 hours.

In my case, i think with the buffer, and a fan controller + hopper filled unit, the need boiler it's self controls when it burns hard, or goes in to idle mode. either way.

antoinolachtnai wrote: »

Is the garage in a separate building? If it is and you can improve the insulation on the piping, you will certainly solve a lot of problems.

If you are losing 10 degrees on the way over and back, then it doesn't matter whether you have a buffer tank or not, you are losing an awful lot of heat to the environment.

It's a rough guess, apologies! should have stated that.

Water John wrote: »

A wood gasification system is different than wood burning. The buffer tank is over 1,500 litrs. You fire it up a couple of times a week. Most can be filled with split log.
It's limiting your fuel cost, I'm looking at.

Look eg BMK

BMK look nice, but the Cost vs return doesnt appear to be there, 2500/3000 for say a 20KW defro , vis 8-9000 for BMK .. unless im looking at the wrong end of the scale ?

Water John

If you can halve your fuel cost, it's €2.5K/year.

Dr4gul4

Water John wrote: »

If you can halve your fuel cost, it's €2.5K/year.

You think they are that much more efficient John ?

Water John

Gasification is highly efficient but its using log timber as your fuel source that lowers your fuel cost.

Dr4gul4

Water John wrote: »

Gasification is highly efficient but its using log timber as your fuel source that lowers your fuel cost.

Again this is why the Duo options are so appealing to me, I can fill it with coal, and she doesnt have to look at it, or I can manually feed it logs given the size of the chamber ..

In theory a win win ! ... in theory