New Gas Fire Question - 7.5kw

SteeleyScott

Hi all,

We've had a Dru Global 100 Gas fire fitted in an extension recently, we had it on for the first time properly last night (we were told to let the plaster dry on the newly made chimney breast for a few weeks before using the fire). Spec :- Dru Global 100 BF

Issue is the we had the fire set to MAX but it didn't seem to be giving off as much heat as id expected, nor did the flames seem that large either. It's a 7.5kw output (94% efficiency) so thought it'd be really warm... It's got me wondering whether it's just me or if something isn't right, so wanted to ask on here.

One thing i did think of was; I recall during the installation they had to put a couple bends in the flue to avoid a ceiling joist. Am I correct in thinking bends like this will affect the draught and therefore could be causing the fire not to run as big as it could? or totally unrelatable? Photos below. (yes that socket was eliminated )





thoughts on the above? or anything else I could consider looking into?


thanks

Ged

Ectophile

You would have to check the installation manual regarding bends in the flue.  It's normal to specify a maximum length of flue for a gas appliance, and then every bend knocks a certain distance off that maximum.

Only the manufacturer will know what is right for their appliance.

njkmr

We had an "in the wall" gas fire maybe 20 years ago and to be honest it gave off very little heat. Ours was open rather than glass fronted so not sure if that makes a difference. Maybe the glass heats up better and emits more heat into the room possibly.
Ours felt like the heat went up the flue so we got rid of it.

tacpot12

Has your gas pressure been checked? 

You might also check that the coals are installed correctly - much of the heat output will be radiant, so the coals have to glow. If they aren't glowing, you won't get very much heat. 

daveyjp

Those types of fire are more for effect than heat I'm afraid. It also looks to be a a very large high ceiling room with lots of glass so it may not be adequate for the volume of the room and U value.

SteeleyScott

Ectophile said:

You would have to check the installation manual regarding bends in the flue.  It's normal to specify a maximum length of flue for a gas appliance, and then every bend knocks a certain distance off that maximum.

Only the manufacturer will know what is right for their appliance.

I'll give them a call on monday and see. Out of interest, bends in the flue outside of what the manual states as acceptable...what sort of symptoms would you usually see?

SteeleyScott

njkmr said:

We had an "in the wall" gas fire maybe 20 years ago and to be honest it gave off very little heat. Ours was open rather than glass fronted so not sure if that makes a difference. Maybe the glass heats up better and emits more heat into the room possibly.
Ours felt like the heat went up the flue so we got rid of it.

Interesting, I looked at a bunch to be honest, but all the 'non-sealed' types required an air vent in the room. I.e coring through the wall so air can get in. I didn't fancy that so went with this type (where I believe it draws air down the flue, oppose to from in the room).

SteeleyScott

tacpot12 said:

Has your gas pressure been checked? 

You might also check that the coals are installed correctly - much of the heat output will be radiant, so the coals have to glow. If they aren't glowing, you won't get very much heat. 

On installation it was yeah, i'd need the sheet infront of me, but i seem to recall seeing '20mbar' when it was tested during install.

Did not know that about the coals. Do the logs and coals, flakes etc go in set positions? or freehand?

SteeleyScott

daveyjp said:

Those types of fire are more for effect than heat I'm afraid. It also looks to be a a very large high ceiling room with lots of glass so it may not be adequate for the volume of the room and U value.

It is on the larger side yes, vaulted ceiling of 12ft or so, room w/L is 5mx6m. But that said I did spec the largest gas type fire we could with this in mind, so opted for this 7.5kw output one. To be fair, we've got 5kw of type22 radiators in there too and they heat up that room just fine when we run the CH.

We had a Nuflame gas fire in our last property, same setup with a balanced flue, and in a similar size room...I recall it being very effective....that's where my concern has come in here. Ensuring there isn't an underlying issue.

EssexExile

Didn't the installers leave you any paperwork? There should be installation instructions and specifications, that will tell you about allowed bends in the flue and coal/log arrangements. If not it's all available online.

SteeleyScott

EssexExile said:

Didn't the installers leave you any paperwork? There should be installation instructions and specifications, that will tell you about allowed bends in the flue and coal/log arrangements. If not it's all available online.

They did, on first glance it went over my head as I only skimmed, it but having read it again it is making more sense. Images of the troubleshooting, and permissible table guide/s attached below.








Im guessing the table for 'permissibility with wall terminal' is irrelevant to me, as my setup goes through the ceiling.

In which case, on the last image 'permissibility with roof terminal'. Hard to say for certain now that I can't measure it, but i'd say there's about 1.8M total vertical, and 0.4m horizontal, 2 bends...which puts us as 'Situation' 'A'.

Reassuringly nowhere near the non-permissible regions, but, I wonder if the restrictor has been set incorrectly, if its already set right then i'm sort of at the limit of air naturally coming in I guess.

The first image does reference a thing called PowerVent though which I assume helps people in situation 'A' the most, it is essentially a fan that goes on the end of the flue, to reinforce getting air in.


Have I understood all that correctly or way out of position here?