I have a boiler that is only providing heat for my heated water baseboard system with 4 zones. I've always thought that the high limit on the aquastat was set too low. The temperature on the boiler reads around 145 when the heat cycle ends. Most of what I've seen on heating sites recommends 180 or higher.
How to know if the high limit and low limit are set correctly on the aquastat
boilerfurnaceheating
Related Solutions
As long as the boiler is capable of providing enough hot water through the system to heat the whole house if necessary you shouldn't have a problem.
What you are proposing is a "coarser" version of thermostatic valves on each radiator and that is perfectly safe for a combination boiler.
I don't think you need return valves.
Make sure that you leave one radiator "open" (usually the bathroom one) so that there is some flow around the circuit.
By the way the fact that it's a combination boiler is a red herring. The "combi" bit refers to the hot water heater, the central heating aspect is pretty much the same as a "standard" boiler with integral pump.
Update
If you want to control the times each room is heated independently you can get combined timer and thermostatic radiator valves - My Greener Home has some for example.
Should the sight glass of a steam boiler always be within the recommended range? Or only when firing
I talked to the guy who originally installed the boiler and he suggested that the pressure was probably a bit high (was set to 1.5 PSI) for our house; if the pressure is too high, then more steam than the radiators can handle is sent out at a time, and therefor the steam doesn't condense back to water at the radiators at first, so the water level gets low and the auto feeder turns on.
I turned down the pressure to just below 1 PSI and it seems to have done the trick, the water level on the site glass doesn't go down as far while the boiler is operating. Also, according to this article, steam heat pressure really does't need to be high at all, so there is no worry on my end about turning it down.
In order to turn down the pressure I adjusted the screw at the top of the box next to the pressure gauge:
Related Topic
- Water – Combination boiler pressure zero after heating
- How does Underfloor Heating get the right temperature water via a Thermal Store
- Connect the C wire from the thermostat when there are two transformers
- Heating HVAC – Is Transitioning to All Electric Heating Smart?
- Banging sound from gas boiler
- How to improve recovery time of the hot water baseboard system
- Water Flow – How to Fix No Water Flow in One Zone of Water Boiler
Best Answer
It all depends on what type of system you are running. The lowest temperature possible sufficient to satisfy the heating load is recommended due to the fuel savings.
To give you an idea
From a NHB service manual
I personally wouldn't set anything contactable to more then 150ish°F.