Hello all, I need to install a grease trap under a commercial sink in a school. Not really my area but needs to be done. There are 2 sinks and 2 ovens that have wastes coming off them with what I belive is a degreaser dispenser. My questions are, would I class each sink and oven as 1 appliance, therefore needing around a 100 litre? I know the manual traps are just waste in and waste out but do I need to put vent pipes before and after? How high does the air intake and vent need to go? Just above the waste traps? With air admittance valves ?
Grease trap
- Thread starter burts
- Start date
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There would normally be a flow control/valve upstream of the trap with the vent up from that, should really be above the spillover level of the sink/appliance. AAV on top of that. Ideally the outflow would be connected to a open vented stack to allow for any positive pressure release. Yes 1 appliance is 1 appliance, unless it is say like a double sink but even then they all need to be trapped. Not sure as to the total number into the trap itself and if it is limited, need to find out about that TBH.
Don't forget to put a blanked tee upstream of the flow control after the trap(s), or have a rodding eye on the run down to the valve, gives you access to the valve just in case it gets clogged up.
Don't forget to put a blanked tee upstream of the flow control after the trap(s), or have a rodding eye on the run down to the valve, gives you access to the valve just in case it gets clogged up.
Thanks for replying, I will have a tee with a rodding point somewhere in the installation. The install is under a double sink, so i won’t be able to get a vent above spill over level, just a above trap level. I’ve never fitted a flow control valve on a waste, will this come with the grease trap?
Also the waste outlet just dissapears in copper in to the floor. I’d assume it’s connected to a vented stack somewhere nearby but don’t know. Can I not again branch off and put an AAV to the underside of the appliance?
Also the waste outlet just dissapears in copper in to the floor. I’d assume it’s connected to a vented stack somewhere nearby but don’t know. Can I not again branch off and put an AAV to the underside of the appliance?
I have only ever installed 2 and they both came with a flow control valve but I'd check with your supplier to confirm and check they have a vent.
If you can you really want to know where it connects onto the soil pipe, it's to allow the grease trap to vent any positive pressure otherwise it may not flow properly so an AAV downstream wouldn't work. You could maybe suck it an see and hope the copper waste downstream is connected to a vented stack quite close, otherwise it could run into trouble if it's all running at max and could blow other trap seals or appliances further downstream.
If you can you really want to know where it connects onto the soil pipe, it's to allow the grease trap to vent any positive pressure otherwise it may not flow properly so an AAV downstream wouldn't work. You could maybe suck it an see and hope the copper waste downstream is connected to a vented stack quite close, otherwise it could run into trouble if it's all running at max and could blow other trap seals or appliances further downstream.
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Will this be a stainless one with the catch tray or one of the electric ones?
We used to have a contract with Greene King to clean them every 3 months, the easiest ones to maintain were about 600x450 square and 300 deep, any bigger and the tray was hard to get out. They had 2” connections either end but no flow control, just gravity.
We used to have a contract with Greene King to clean them every 3 months, the easiest ones to maintain were about 600x450 square and 300 deep, any bigger and the tray was hard to get out. They had 2” connections either end but no flow control, just gravity.
2 more than me
I guess the worst that will happen is a callback regarding traps blowing etc. Then I could probably take an 1 1/2 Waste out the wall and vent up the side of the building. The allowance is within 6m Of a vented stack isn’t it?
Ian this will just be a manual grease trap. So as you say, a 2inch inlet ans outlet, with the additional vent requirements. I guess I just use the rubber coupling with jubilee clips.
I’ve read that as it’s 4 appliances it will need a 100 litre which is 800 x 400 x 320. Does this seem overkill for 2 sinks and 2 ovens ?
It does to me, the staff in the pubs should clean them everyday but they don’t.
In my opinion the smaller ones are great and easy to maintain, the big ones are hard work and the internal ‘in the floor’ ones are just plain stupid.
I just got this off google, this design seemed to work the best with a big basket on the inlet:
In my opinion the smaller ones are great and easy to maintain, the big ones are hard work and the internal ‘in the floor’ ones are just plain stupid.
I just got this off google, this design seemed to work the best with a big basket on the inlet:
Ian I was led to belive that size isn’t dependant in how often they are cleaned but the flow rate of the appliances, if the trap isn’t large enough then it could back up
Ian I was led to belive that size isn’t dependant in how often they are cleaned but the flow rate of the appliances, if the trap isn’t large enough then it could back up
Possibly, i’m not sure how they size them originally but I can’t see how the capacity will matter if the inlets and outlets are all 50mm. I guess the grease has more space to settle.
I think it’s exatly that theory. If there is more grease then it will take longer to separate and therefore slow down flow and needing a bigger trap.
Anyway, there is a Rational self cooking centre and a combi master. The spec says max flow rate 6.6 gpm on both so guess if sizing like that then the larger grease trap is far too big. Will put a smaller one in.
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