Office / Shed Heating

[Ajn]

An observation for those that need to heat a work/office shed during the self build process.

We have a timber garden buiding, 5mx6m, that we used as a lounge room duing our restoration while living in the caravan. This had a 6kw log(s) burner which worked very well over a couple of winters provided it was lit early, had more than one log on it, didn't let it go out and had plenty of logs ready. Last winter this fire was moved into the main building inplace of the intended log burner that was now out of scope for the budget.

 

I was intending to use part of the garden room as my hobby shed. With a budget of around 200 quid, we had a choice of either finding another log burner, using an electic fan heater, staying in bed or finding something else. The something else is a 8kw Chinese diesel cab heater.  I put the heater on the inside with the burner air intake and the exhaust through a couple of proctected and sealed holes  to the outside. The 10 ltr fuel tank and pump also on the outside. These heaters are 12v (24v available), I used a 240v to 12v 20A supply set at 13.8V foating a used mobility scooter battery. These heaters require a shutdown process, the battery provideds that should we lose power. It will also run the heater for a few hours.

 

Key thing for here though and the reason for this post is the cost of running it. It says 8kw on the box but it is not. It is six at the most.  From 5 degrees C  it will get the temp to 19 in about an hour. I have run it on heating oil (kerosene) for just over 100 hours and it has used 0.505 ltrs per hour avarage over that period. The oil cost £1 per ltr. So 50p for 6kw per hour does not seem bad given 34p kw of electric would have been £2.04.

 

All in cost has been less that £160.  The power unit, a fuel cutoff and second filter included in this cost.  Much better than a LPG heater as it does not fill the air with water.

[SteamyTea]

1 hour ago, Ajn said:

says 8kw

 

1 hour ago, Ajn said:

used 0.505 ltrs per hour avarage over that period

That will be about 5 kW then.

 

You may get a higher power output if the inlet temperature was very low, and the air very dry.

[JohnMo]

That's a big heat input into a small space, take it has little or no insulation?

[Adrian Walker]

4 hours ago, Ajn said:

An observation for those that need to heat a work/office shed during the self build process.

We have a timber garden buiding, 5mx6m, that we used as a lounge room duing our restoration while living in the caravan. This had a 6kw log(s) burner which worked very well over a couple of winters provided it was lit early, had more than one log on it, didn't let it go out and had plenty of logs ready. Last winter this fire was moved into the main building inplace of the intended log burner that was now out of scope for the budget.

 

I was intending to use part of the garden room as my hobby shed. With a budget of around 200 quid, we had a choice of either finding another log burner, using an electic fan heater, staying in bed or finding something else. The something else is a 8kw Chinese diesel cab heater.  I put the heater on the inside with the burner air intake and the exhaust through a couple of proctected and sealed holes  to the outside. The 10 ltr fuel tank and pump also on the outside. These heaters are 12v (24v available), I used a 240v to 12v 20A supply set at 13.8V foating a used mobility scooter battery. These heaters require a shutdown process, the battery provideds that should we lose power. It will also run the heater for a few hours.

 

Key thing for here though and the reason for this post is the cost of running it. It says 8kw on the box but it is not. It is six at the most.  From 5 degrees C  it will get the temp to 19 in about an hour. I have run it on heating oil (kerosene) for just over 100 hours and it has used 0.505 ltrs per hour avarage over that period. The oil cost £1 per ltr. So 50p for 6kw per hour does not seem bad given 34p kw of electric would have been £2.04.

 

All in cost has been less that £160.  The power unit, a fuel cutoff and second filter included in this cost.  Much better than a LPG heater as it does not fill the air with water.

that’s a lot of energy in a small space. How much insulation do you have on walls, floor & roof?

[Ajn]

54 minutes ago, Adrian Walker said:

How much insulation do you have on walls, floor & roof

walls just 38mm timber, roof has 100mm, floor has the same. This is just a temporary location for my activities so no plans for any structure improvements untill the whole building is moved in a couple of years.

[Ajn]

4 hours ago, SteamyTea said:

That will be about 5 kW then.

Realy don't understand the point of that statement as it's an avarage anyway. What point are you trying to make?

 

[dpmiller]

IIRC those webasto heaters throttle themselves depending on DeltaT (pump is pulsed) so unless you can keep it's intake air stone cold and the fan up full, it's never going to run at the max. They're great heaters, very clean burning.