Ermi this thing is like system balancing it will run forever.
I see it this way and perhaps you who has had a lot of experience in both Commercial and domestic, you may agree in part with me.
If you are using two boilers on any system it's got to be a LLH
If you are putting a single new boiler on an old system and its flush out do you need a PEX to separate the old crappy system
from the new boiler. My take on it is no you don't.
If you flush the system and put a mag filter on it surely that should do, do boilers fail early in life because the HX fails, I don't know perhaps some of you out there know more and do HX fail early because of a dirty system or just poor flow rate across the HX from day one. I have no doubt if you guys are fitting bypass valves you will never know if the correct flow is going through the boiler ever you have no way of measuring it, you know if its not good when the boiler starts to kettle, unless you are deaf.
If you fit a LLH on a single boiler you can almost be certain the water flow in the boiler side will not drop at all, as long as you fit the correct size pump on the primary side, so the LLH is a plus then, but it means using two pumps and the cost of the header, does the custard want to pay for that, what the cost of a boiler over say 5 years not too much and how long do the new low water content boiler last.
I think if you try and get as much crap out of a system as you can, fit the magic mag-filter the boiler should last 10 years at least as long as you make sure the flow rate is OK, incidentally all manufactures put 2 thermistor on their boilers to try and calculate the min boiler flow rate, it's crude but it is a cheap way of having a bash at it.
What do you think Ermi???
Perfection is good to have I agree, but your are in a crappy old business, who will do the job the cheapest
