Some corrosion cases are due to most of the radiators in the house being turned off without pump performance being adjusted.
This can result in water pitching from too low an open vent into the feed / expansion tank and gaining oxygen in the process.
Increasing the height of the open vent sufficiently has solved the problem.
Of course the open end is piped back down to just within the expansion tank. Not just left pointing in its general direction.I have corrected systems with inadequate open vents that may have been pitching since date of installation
and it is very sad when the client also has to seek advice on drying out and treatment of wetted roof timbers.
Amount of condensation damage will depend upon the operating temperature of a such a system.
A self regulating pump or pressure differential by-pass valve properly installed,
ensures satisfactory operation, regardless of the number of radiators used.
Ask your plumber.
An open system that is heavily sludged up may pitch regardless.
Pumps
Do you have thermostatic
radiator valves?Now available are pumps
that self-regulate to suit
the number of radiators
in use.This prevents excessive
system pressure differentials
which can cause ingress of
air or pitching.It costs a little extra but is
well worth it.Hot water cylinder stone cold every morning ?
and attic room radiators hot long after the heating is off.I have found pipes to upper radiators, taken off at too high a level
from the primary flow and return near the hot water cylinder.Or the presence of a rising primary vent in the roof space was too convenient to resist.
( If it was an open system)
I suppose it's possible to have a circulating pump that is running twenty four hours a day,
with the timer switching your boiler on and off.
That would cause the cylinder to give up its heat to the entire system once the boiler is off.
But you should hear a pump running at night ?A system in south Dublin, had the pump
switching on and off via a room thermostat 24 hours a day.
Heat gravitated from the hot water cylinder, to upper radiators at night.
The gas boiler alone was controlled by the time clock.
The poor occupant was being woken in the middle of the night
when the temperature dropped, the pump started up and proceeded to
dissipate what little heat was left in the cylinder to the entire system.
Some heating systems ( Especially with solid fuel boilers ) have pipe-work
within which gravity circulation is intended to occur.
In my opinion Only an experienced installer should be asked to make changes to such a system.
Sealed System. (Pressure Vessels)
A common sight in Dublin.
Rusty water coming from
a boiler safety valve is
a sure sign of corroded
radiators. Caused by a
neglected pressure regulator
and / or expansion vessel.
I do not assume that a new vessel is charged with air / gas.
I always check for correct pressure prior to fitting.Only when commissioning.
If water pressure is rising too rapidly
in a new installation when the system is
heating up I release a little air / gas until
expanded warmer water can be felt
travelling down into the vessel.I would ask any boiler experts not to let
the precious air out of the vessel unless
you have the means to pump it back in.Some recently installed sealed heating
systems would appear to have inadequate
expansion provisionMany boiler install guides unfortunately
use the word optional when speaking
of additional vessel capacity.Boiler safety valve discharge
is often ignored.
Sealed System. (Pressure Gauge)
IF a heating system is fed from the incoming main, it is advisable
for the pressure gauge to be clearly visible from the manual fill point.
Yes there's probably one there already
near the little isolation fill hose and non/return valves.
In the Dublin area I often find heating systems fed permanently from the rising main? Water undertakings do not permit this.
A proper isolating kit is fitted. The pressure regulator if left
in place can ensure that the system is not manually over pressurised.A lever action valve will clearly show Open or Closed ?
w
Safety Valve Discharge Pipe.
There is a female thread in the outlet of most boiler safety valves.
This enables discharge to be piped to a position where it
cannot scald or drown you, or damage property.
This is especially applicable to the sealed system.
fed from the rising main . Someone may forget to isolate it.Beware. The air or gas voids in the radiators of a neglected sealed system often serve to accommodate expanded water
when an expansion vessel has failed.I always check the vessel before venting radiators completely. Boiler, Pressure vessel and any heating feed arrangements would preferably be on the ground floor of any property where they will both function better and certainly do far less damage to property in the event of leakage.
Such simple installation principles are often ignored at great cost to all.Loss of pressure. Attic room rad not heating ? A heating fill point may be discovered lurking in the attic insulation. Such fixed pipe-work between the rising main and a heating system is contrary to water regulations.
A filling loop should certainly not
buried within attic insulation.
Common steel tank arrangement.
Prior to adding any corrosion inhibiting chemical to a feed / expansion tank I check the overflow pipe from same.
If set to discharge down into the plumbing tank I re-pipe it to discharge externally.
I prefer to raise the height of the plumbing tanks to improve gravity shower performance.
Also eliminating the need for noisy pumps.A lower feed expansion tank will prevent heating
water / chemicals passing into the bath water in the event of a perforated cylinder coil.
Water will pass from the plumbing to the heating system exiting the feed/ expansion tank overflow pipe.With the higher pressure sealed system we have to be alert for failure of the coil in the domestic hot water cylinder with water / chemicals passing into the bath water.
Thankfully a rare occurrence.An ancient gravity hot water cylinder will contain a multi-piped heat exchanger.
Some of these were solder assembled and are prone to failure upon becoming part of a sealed system.A Jetfreezer kit enables me to quickly inspect and correct suspect joints.
Especially since a pipe upstairs fell out of a rad valve and nearly bought the ceilings down.
This miss-aligned joint certainly needs attention.
Things to consider!
The heating is allowed to cool. The valve above is initially left open to allow for the rapid expansion of water as it falls from 4deg C to Freezing. This occurs either side of the ice plug.
This water expansion is left open to any air pocket at the top of the radiator.
Or I may leave a rad vent weeping.I may close the valve at the other end of the rad to stop any gravity circulation which slows freezing.
I wrap the jacket around the pipe
and inject Co2 liquid into it until I feel dry
ice build up within the jacket.
I wait for a while occasionally squeezing
the jacket to maintain good dry-ice contact
with the pipe. (wearing protective gloves)
After 3 to 5 mins an ice plug forms within the pipe.
A horizontal pipe will freeze much quicker than a vertical pipe.
One should study all the Co2 suppliers
safety literature before use.I have used dry-ice pellets within an old
padded jacket or duvet to freeze, cut, thread
and valve off some large steel heating pipes.
Co2 bottles and Dry-ice Pellets are available from the ever help-full BOCDry-ice must not be touched with bare hands,
it can cause severe burns.It does not melt. It simply evaporates
to become a heavy gas which clings to the ground.
Note! Co2 can displace oxygen when used
to freeze pipes in a tight excavation.
Do study the relevant safety Safety Datasheets
