Hey, i have a 4500 square foot 5 bedroom home and need a new boiler. I currently have a system 2000 with 8 zones that is a piece of garbage and I can not get parts for it. It's 20 years old and can not be vacumed as we can not get the back section parts that have deteriorated to the point where we can not take the back off to vacum. There's only 1 place around here (boston area) that we can get parts from for this POS and they will not let us order parts unless we buy oil from them under contract and I refuse to be straight armed into such an agreement. FU&% them! I don't mind seeing this thing go and welcome a new boiler. My plumbing HVAC guy is reccomending an Ultimate Boiler PFO-7(by ultimate) which is an energy star 89 percent eficient boiler and a Superstor for the hot water. He's quoting me 8500 bucks for the job. He said he will put in all circulators (8 zones) and no zone valves for a balanced system. What the heck does that mean? Is Ultimate a good boiler? Are circulators better than zone valves? WHat about the superstor? Thanks very much. I'm getting 2 other quotes also. I don't mind paying a bit more for eficiency and quality. I understand that the US avergae for a new boiler and water heater parts and labor is 6 grand. This quote is obviously higher than that, but again, it's a decent size house with 8 zones and I'm assuming that the boiler is top notch??? So many questions! Thanks in advance for the advice.

I know there is a way to control it with mixing valve for example etc, but why some manufact. do not have any provisions/mention it in their manuals? How important is it? I have Buderus boiler( cast iron) and in my manual there is no return temp requirements for low volume systems, <115 gal. How many of you control your return temp? I guess it only applies to boilers with set low limit (not for cold start boilers) Below is Buderus manual link Can somebody explain me table 3.2.1 please? They specify min boiler temp, 150", I doesn't make any sense as they control it with 8148 (cols start stat), see page 51. Boiler can cut off at 130 as long as thermostat satisfied when used as a cold start? Also in the same table they stating mixing valve is necessary (for aquastat applications). Is it only for low temp circuits? At the same time column 4 says that return requirement is only for large systems? Do I need to maintain return temp or not? If yes, would indirect zone by itself sufficient enough to maintain proper return temp? http://www.buderus.net/Portals/16/Final%20Version%20G115%20(new)%20Installation%20Manual%20062204%2063030586.pdf