We had a new high efficiency boiler installed a couple years ago to include an outdoor reset & have been wrestling with extremely loud creaking/fast ticking noises in the upstairs zone of a 3 zone system ever since. The downstairs zone is quiet & the third zone is the garage which has a fan & is loud anyway. The loud noises were not there with the old boiler. The dealer who installed it doesn't have the answer. They concede it is extremely loud but said it's just expansion, again it was not there with the old boiler. They installed a variable speed circulator trying to slow down the start of the water circulation cycle but that didn't help. It was set in the "Delta T" mode with a 20 degree differential, no help. I since have lowered the Temp of the boiler to 180 degrees & set the reset at 85%. With a 45 degree temp outside the boiler shuts off at 168. I also switched the mode on the circulator pump to constant speed set for an 8' rise at 12 gpm. The initial start of the pump in the Delta T mode would be 55-60 watts compared to the 20 in the constant speed mode. It seems to make no difference. It doesn't sound like like air in the system but I went ahead & bled it anyway. It just baffles me how the upstairs zone can be so loud & the downstairs quiet. Any ideas would be greatly appreciated.

The heating elements in the baseboards sit in cradles. As the elements expand they slide on those cradles and make the noise. Cut some strips from a plastic milk jug and put them between the element and the and the cradles. Make sure there is space in the flooring where the piping goes through. You may have to use a keyhole saw and create some clearance there.

On a different note....There is a lot of science involved when properly installing a hi-efficiency boiler running on outdoor reset. A room by room heat loss calculation must be done to make sure the boiler is sized correctly. The emitters must be sized so that at design day temperature(coldest temp for your area), they satisfy the heating needs of the home with 135 or less degree water. If the boiler is running at temps above about 135 degrees, it is running at standard efficiency, 85% maximum. When done correctly, you don't even need a thermostat in the house.

Thanks for the response Paul48, I'll try the milk jug cradle bushing.

I'll have to read up on the more technical part of your response, I haven't been that deep into the sizing or calculations.

if no changes were made to the upstairs piping then I find it hard to believe the new boiler is the cause of the expansion noises.
these type noises are very common where copper tubing rubs against wood.
if the noise is coming from the baseboard heaters where the elements sit on their respective brackets, you can make sure there is something between the element and the bracket. as paul suggests, pieces of plastic milk bottle will work. you can also use small piece of pipe insulation.
if the noise is coming from the location where the copper come up thru the floor then wedge something between the pipe and the wood.
if the pipes are rubbing where they come thru a hole in an inaccessible location, there is not much you can do about it.
I do think the outdoor reset option is set too high.
168 is too hot when the outdoor temp is 48 deg F.
I would think 135 would do it.
so much depends on the amount of sunshine and the wind direction that setting the outdoor reset control is not an exact science.

The best way I have heard to set up the reset curve, is to crank the thermostat up as high as it will go. Then adjust the high and low of the curve until the boiler will maintain the house at a comfortable temperature. Avoid using setbacks at night. Because you are only putting just enough heat into the home to make it comfortable, if you let the furnishings and everything in the house get colder at night, you're actually working against yourself. I've seen copies of proposals from some very skilled heating contractors and they are amazing in their detail.