Buffer tank, riiiiight.

Add radiation to the basemen with an option for zoning. This will help properly load the boiler and make basement and the floor above warmer. A buffer tank is a crutch, both painful and awkward.

Investing in radiation will make the cycle time longer and you warmer.

Another great argument for proper, professional, ACCA Manual 'J' heat loads, before buying any boiler or furnace.

Buffer tanks are actually embedded in many heat sources causing them to be high thermal mass heat sources (e.g., Versa-Flame). However, when low thermal mass heat sources are combined with zoned hydronic radiant distribution systems, it is possible for the heat source to short cycle when only a couple of these zones call for heat. This occurs because the rate of heat produced by the heat source is much greater than the rate of heat used/released by these zones. Low volume thermal mass heat sources in combination with low volume hydronic circuit and distribution systems cannot absorb this excess heat rate without experiencing a rapid rise in temperature. This causes the heat source to reach its high temperature limit very quickly resulting in very short ON times and short cycling. So for the case where you selected a low thermal mass heat source and where you already have all the hydronic emitters that you need, the only solution is to add a buffer tank.

So while a heat loss analysis is always the first step in a hydronic radiant floor heating system design, there are also many other design steps that actually have to be accomplished to ensure having a successful design. I doubt many “professionals” know how or often bother to accomplish these required steps.

I did the math it looks like I would be looking at a 20 gallon tank with the present system or just a 10 gallon tank for the 2nd zone if I added the baseboards from zone 1 . Do they even make buffer tanks that small??

20 gallons is the smallest we have used.

Vaughn

However, I am still thinking that the "do nothing" option may be your best option (or add some more radiators) unless your cycling decreases from what you indicated.

Then it's settled...baseboards in the basement and live with it! Many thanks to Dan for the very helpful pump adjustment advice.

Is this boiler completely shot of with 2 winters of this happening? Only time will tell I guess.

Only time will tell, but I wouldn’t lose any sleep thinking about it!