reasons for low OG for first runnings

[JLem]

I just tried my first no-sparge brew. It was a small batch, only intended for 3.5 gallons. It was also a pumpkin beer, so the grist contained some fresh pumpkin (grated using a cuisinart). I know that overall efficiency is low for no sparge brews, but mine was abysmal. The OG of the first runnings was a paltry 1.040.

Here's my grist:
5 lbs Pale Malt, Maris Otter (3.0 SRM) Grain
2 lbs Pumpkin, fresh (3.0 SRM) Grain
1 lbs Caramunich I (Weyermann) (43.0 SRM) Grain
8.0 oz Melanoidin (Weyermann) (33.0 SRM) Grain
8.0 oz Vienna Malt (3.5 SRM) Grain
8.0 oz Wheat Malt, Pale (Weyermann) (1.4 SRM) Grain

I used 16 quarts of water and my mash temp ended up on the lowish side (148-149), but after 60 minutes I had full conversion (iodine test). Shouldn't this amount of grain yield a higher first runnings OG? I used Kai's chart here (http://www.braukaiser.com/wiki/index.php/Understanding_Efficiency#Conversion_efficiency) and figured on a much higher OG. In the end my efficiency was only about 34%. I had expected something in the 50-60% range.

Given that I got full conversion and that the OG of first wort runnings is independent of volume (though I realize that volume matters when calculating brewhouse efficiency), I am assuming that my crush was not particularly good (in fact, terrible). Does this seem reasonable? Am I missing something else?

 

[TipsyDragon]

i assume you do allot of AG brewing. if so i would agree that the crush being the culprit sounds reasonable. the finer the crush the easier it is to get to the sugars. if you don't do allot of AG i would look into the efficiency of the mash tun. is it draining from all parts of the grain bed evenly? is there a big dead spot in your mash tun? are you draining to fast and compacting the grain?

 

[ScottD13]

What was your expected og? How much wort did you collect? Is this based off a recipe that you've done in the past? If so what was that recipe. I've read that with no-sparge you have to bump your recipe up by at least half...

I've been considering trying some no-sparge too and will keep an eye on this thread.

 

[prosper]

I actually get pretty decent efficiency when no-sparging, 75-80% (which is about 10 points less than my 'normal' efficiency). Efficiency suffers a lot more for higher gravity (>1.060) beers.

Could you tell us more about your process?

 

[JLem]

I'm not really complaining about overall efficiency, which I get is a function of the lautering process. What struck me as odd is that the first runnings were only 1.040. Regardless of how much wort I manage to collect (which will go into calculating my overall efficiency), I expected this number to be much higher.

I mashed 7.5 pounds of grain plus 2 pounds of fresh, grated pumpkin in 4 gallons of water.

To answer some of your questions:
This was my first AG attempt. Since it was no-sparge, I assumed I would only get 50-60% efficiency and adjusted the recipe accordingly. In the end, I only got 34% overall efficiency. I collected the volume I calculated I would (2.5 gallons), but the gravity of the first runnings was nowhere near where I was thinking it would/should be. This was my first attempt at meshing AG with my limited stove-top boil volume. I have the math all worked out and it should/can work as long as my assumption about the first wort runnings is accurate, which is where I seem to have failed this time.

Given this grist and this mash volume, what would you expect the first runnings to come out as?