Outdoor boiler with shallow buried pipes

steamboat

We bought our house new 9 years ago. OFCH with outdoor boiler. During the big freeze winters a couple of years back I noticed a path would melt in the snow from the outdoor boiler to the house above where the pipes ran. There must be a serious amount of heat being wasted. This week we began digging up the garden to lay some paving and I was amazed to find that the pipes were pretty much laid right under the top surface... no more than 6 inches deep. These are standard pipes with basic foam insulation. Anyone know if there are building standards or regulations around this? God knows how much heat has been lost over the last 9 years! Attached a couple of pics. You can see the pipes into the house go right beneath the footpath.

esox28

You have basicly three options...

Move boiler to the footpath pipe from boiler to internal through external wall eliminating piping in the ground.

other options are but you need to understand that the piping is okay laid in the ground as it is, its only when the ground becomes wet that major heat loss occurs, the cold damp ground will absorb 10 times as much heat as dry ground (so its most of the time here).

In order to have your piping in a water tight duct you will need to use 4" sewer piping which will termanate internally in the house and internally within the boiler, having installed the boiler pipe and insulated with 19mm x 22mm armaflex insulation into the sewer ducting.

Last option and quite difficult to use in short runs is a 'duo' pipe or district heating preinsulated pipe, some of the piping have the advantage of a heat shrink water tight termination end caps so it can be laid without the need to terminate internally, but only on the more expensive types.

corkgsxr

Dig the pipes so you have space underneath.

Get solar grade armaflex. Cover pipes.

Cover them with sand. So its underneath and around the pipes.

soil over that.

The sand wont hold water so less heat loss. The armaflex will do the rest.

if you really wanna go for it. Get 4" armaflex and wrap it around the already covered pipes.

steamboat

Thanks for the advise guys. I uncovered more of the piping today. It meanders around a bit before entering the house, following the edge of the footpath rather than taking the most direct route, so there is more length than necessary. This extra length does give some room to maneuver however. I'm thinking I'll reposition the pipes to go direct from boiler to the house in a much deeper trench (18 inches or so), add the extra layer of armaflex and surround in sand as suggested before filling with soil. Seems like the best approach without having to reposition the boiler or change the piping.

air

Outside boilers are the work of the devli, however there probably isn't much you can do with regard to moving it inside.
I'd be inclined to go with the sewer pipe approach myself to be honest but it might require major upheaval indoors?

Put it in as deep as practical with as much insulation on the pipes as possible and then back fill the inside of the pipe with perlite if you can get it.
You could fill below and around the sewer pipe with perlite also, it is far less thermally conductive than sand and is free draining.

DGOBS

Really, I would think an outside boiler is a much better idea, as reduce CO risk, reduced fire risk, reduced damage for the house with an oil leak, no underlay odour (as there is always a 'boiler' smell' IMHO), less hassle for the householder for servicing, less infringement on household space.


As long as the outside boiler is fitted adjacent to the outer wall of the house with little or no outside pipework, and zero loss insulation applied where required.

The only loss is efficiency gain in the kitchen/utility from the appliance casing, which at best is 3% (less with properly insulated external appliances, but IMHO the loss is certainly worth the safety gain.

air

I'd agree that an outside boiler might be a better option if fitted in that manner, however I've never seen one fitted anything like you have described .
Most of the ones I've seen could more accurately be described as patio heaters with secondary home heating functionality!

corkgsxr

I wouldn't fit a oil boiler inside unless I had no other choice

DGOBS

Outside boilers are the work of the devli,

I'd agree that an outside boiler might be a better option if fitted in that manner, however I've never seen one fitted anything like you have described

So essentially what your saying is the INSTALLERS of outside boilers have a lot to answer for, but outside boilers are a better option on the whole.....not the work of the devil!

air

Yes, I'd agree that it is the poor installation practices that are the problem, however as mentioned I've never seen one well installed.

Not withstanding this though, it would be better to have the boiler within the thermal envelope of the house. There's no reason a boiler couldn't be incorporated within a small air tight fire proof room accessed off a utility room.

There is no such thing as "zero loss" insulation, and installing internally means that the majority of the losses will be lost to the house, so not really lost at all.

DGOBS

There's no reason a boiler couldn't be incorporated within a small air tight fire proof room accessed off a utility room.

Surely once this is achieved the 2-3% case loss from being outside wouldn't do very much for you as it would be in fireproofed enclosure that would need ventilation then to outside the property (ie. oil boiler installed in a compartment requires ventilation)

Zero Loss is a term used for specific insulation materials for external pipework (does not infer as the name suggests)

To me, simple safety over efficiency, you are saying on one hand that these boilers (externally) are not fitted well, or correctly, but then expecting the same installer to address internal issues to bring an internal appliance to the same safety as an external one would be an act of futility (different boat, same crew, so to speak)

I have seen numerous boilers installed both internally and externally eel, correctly and efficiently, whether internal or external, poor installations are unsafe, inefficient and sometimes dangerous.

shane 007

air wrote: »

Yes, I'd agree that it is the poor installation practices that are the problem, however as mentioned I've never seen one well installed.

I seen plenty & have installed plenty too.

air wrote: »

Not withstanding this though, it would be better to have the boiler within the thermal envelope of the house. There's no reason a boiler couldn't be incorporated within a small air tight fire proof room accessed off a utility room.

My first option would be a purpose built boiler house attached to the house or a balanced flue boiler in a garage attached to the house. My least favourite is having the boiler within the house. Oil boilers are all too reliable & many are only serviced every 7-10 years or when the break down whichever comes first. Even when serviced, many are just so-called "serviced" with a quick clean & nozzle change.

air wrote: »

There is no such thing as "zero loss" insulation, and installing internally means that the majority of the losses will be lost to the house, so not really lost at all.

It is referred to as "zero loss" pipe due to the fact it loses only 1C over 50m pipe run. So in a pipe run from an outdoor boiler into the house would be generally under 5m, the loss would be negligible.

Fitting pipes within 4" or 6" soil pipe & squirting a bit of expandable foam in is a waste of time. The pipe needs to be exactly centred within the pipe to be completely enveloped in insulation & the insulation properties of that are very poor.
Tubolit is not much better.
High performance Armacell is good but the detail at both ends of the soil pipe is rarely considered & any moisture that can get in, you might as well not have any insulation at all.

shane 007

Sorry DGOBS, was typing at the same time as you.

jimf

I could happily live with those kind of % losses for peace of mind with an outdoor boiler