Last Year we had our first Litter of Pups and one of the most puzzling things that I found was "what temperature should the whelping box be". All the internet information gave a figure of around 80 / 85 degrees, and subsequently I heated the whole area to this temperature.  As someone who would normally not have much heating on even in winter I found this stifling, as did Mum and I believe as did the Pups. After every meal they would attempt to get underneath the Vet Beds and on to the much cooler floor. The whimpering and effort to do so was so intense I had no choice but to allow them to do this. Once on the floor the whimpering immediately stopped and off to sleep they went, so I am convinced that they felt this was too hot. Once asleep I then returned them to the Top of the Vet Beds. Mum perhaps did not spend as much time with them as she should have but as a novice I am unsure. She most certainly was keen to move away and on to the floor, but laid very close to the box. As I am now considering a second litter does anyone have any views on this.

We used a brood lamp for our puppies and had a thermometer on top of the pig rail in the box to keep an eye on what the temperature was right there,  ON THE FLOOR of the box.   We often had to drape a sheet across the back of the box for mum to lie under or she'd get too hot under the lamp.   One clue about the puppies was when warm enough, they'd nurse and then crawl away from mum to lie scattered around the box.   Certainly they'd not crawl under anything.   When too chilly, they'd snuggle up with mum or together if she was out.    All this during the time they weren't old enough to be regulating their own heat.   I also found the brood lamp kept the box  less damp (pee that mum didn't clean up).

Internet information, like the amount of food on bags, should only ever be used as a guide.   Each litter being unique, even if from the same mum!!

I believe this to vary within the breeds.
My breed is a short-coated breed which thrives on heat, so I suspect would 'cope' with a higher temp than other breeds. We have always used an infra red lamp set at a height to suit but lowered or highered depending & also leaving a space where either mum or pups can move to a cooler spot.. We have never used the heat pads but I know some prefer to use them. We also always use vet bed as this can help a lot with keeping mum & pups warm(I see that's what you also use;) )....

I have a Nordic breed with a double coat, and have found any more than 22'C in the room next to the box was too high, very upset pups and Mum.

My 12 day old pups are now down to 18'c and a heatpad in corner that provides just background heat.

I use an oil filled Electric radiator next to the box (on thermostat) to heat the room, as I only have Central heating on to 17'C for around 8 hours a day in the rest of the house.

Whelping box which is like a cave (puppy panels round and over top with blanket covering, so no draughts.  Puppies have been spreading out for the last week, so obviously warm enough.  bitch as I would expect was with pups constantly for the first 3 - 5 days then lay outside the box..

I use shredded paper in the box as Mum will not tolerate the Vet bed I keep trying and I worry about pups getting trapped under it when she digs it up.

I expect in a few days she will let it be, sems to vary from bitch to bitch.

I set my box heating up like we do for animal enclosures at work by having one side of the box warmer and one side cooler. I had my warm side originally set to whatever the book of the bitch recommended and the cooler side was a few degrees colder. I found my pup (singletons) rarely spent time on the warm side, he was either in the middle or on the cooler side most of the time untill I started raising the lamp higher to lower the temp.

The puppies will tell you if they are warm enough, too hot and they spread out round the box and too cold they are piled in a heap and restless as they try to get in the middle. I have never used extra heating,  a room temperature of 20 with a snug cave (cardboard/wooden box with removable top) has been fine for my different short and thick coated breeds.

> a room temperature of 20 with a snug cave

I am glad I am not alone. 

I wonder also how on earth a  bitch in the wild would get her den up to such heat as suggested, where the 20'C seems far more realistic.

I do have the heat pad in the corner of the box should they need it, and now at two weeks am reducing the temperature of supplementary heat that kicks in when Central heating is off.

It's currently 18'C and they are lying in a loose heap, but off the heatpad.

I have a thermometer in the box but it's just for information - I don't try to control the temperature of the box at all.

I watch the behaviour of the puppies - if they are all clumped together in a pile, they may be cold.  If they are distressed and spread out everywhere, they may be too warm. 

The temperature in the whelping box is often warmer than the room, because of the walls of the box, the heat from the mum and pups gets trapped in it - especially if you are draping a sheet over one end of it like we did, to make a bit of a cave.  I was in the whelping box with the dam last time during whelping and was amazed how hot it was in that box, compared to the kitchen outside - I was pouring sweat. 

I rarely need a heat pad but I have one if needed.