GB2366858A

GB2366858A - Connection arrangement for a boiler to a pipework system

Info

Publication number: GB2366858A
Application number: GB0016892A
Authority: GB
Inventors: Nicholas Julian Jan F Macphail
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-07-11
Filing date: 2000-07-11
Publication date: 2002-03-20
Anticipated expiration: 2020-07-11
Also published as: GB2366858B; GB0016892D0

Abstract

The arrangement comprises linking multiple boilers 2 on a loop header 1 having their flow and return pipes 3 linking to the header 1 so that thermosyphonic action or gravity check valves 11 prevents heat flowing from the pipework system to waste via an inactive boiler. The arrangement may comprise either, the header 1 running above the boilers 2 so that thermosyphonic action prevents unwanted heat flow or the header 1 running below the boilers 2 and unwanted heat flow being prevented by check valves 11.

Description

<Desc/Clms Page number 1> THIS INVENTION RELATES TO IMPROVED MEANS OF LINKING BOILERS TO A HEATING SYSTEM It is common practice, when improved load matching with its attendant improved efficiency or where reduced plant space or breakdown standby is required, to link more than one boiler to serve a heating load. Usually this linking involves complicated arrangements of motorised valves and controls without which the heating water will flow through any of the linked boilers that are not active causing considerable heat wastage via convection to their flues and via radiation from the boilers and pipework which would negate the efficiency gain that multi boiler configurations can offer. The cost of motorised valves together with the complexity of their attendant controls, increased risk of control breakdown and the need for more specialised installation, commissioning and maintenance has limited the application of multi boiler installations to very large projects.

It is the aim of the present invention to improve or obviate the above problems.

It is known that the pressure differential between two points on one side of the pump of a closed pumped circuit reduces the closer those two points become and that on low resistance large bore parts of such a circuit two points as close together as three feet produce a differential pressure that is effectively zero.

In smaller or domestic installations linked boilers offer the advantages of higher efficiency by load matching, the security of breakdown standby, quieter domestic boiler usage, greater location choice, the option of balanced flues and physically smaller boilers.

According to the present invention there is provided a loop header where the heating circuit water can circulate whenever a heating circuit is active. Two or more boilers, preferably with shunt pumps, have their flow and returns joined into a single pipe of the looped header close enough so that their differential pressure is effectively zero. Therefore virtually no hot water is caused to flow from the header through any boiler and shunt pump when they are off.

Preferably where the loop header that forms part of the present invention is sufficiently high in relation to the boilers differential temperatures would ensure that thermo-siphonic action would transfer any heat from any boiler to the header and not the other way round, thus ensuring that heat is not wasted by any inactive boiler. Advantageously where the loop header that forms part of the present invention is sufficiently low in relation to the boiler that differential temperatures would cause thermo-siphonic action to transfer heat from the header to the boilers such thermo-siphonic action maybe prevented by a commercially available "gravity check valve" which will prevent heat from the header being transferred to the boiler thus preventing heat being wasted by any inactive boiler. Conveniently on smaller or domestic, for example, twinned boiler installations where cost and simplicity for client understanding are high priorities a "poor man's proportional" control may be used where one boiler thermostat is run at a lower temperature (typically 10 degrees Fahrenheit lower than the standard 180 degrees Fahrenheit) so that under start up or high load conditions both boilers will run while under part load conditions only one boiler will run. Advantageously the lead lag on this arrangement is changed at boiler service intervals. Advantageously on larger installations the full facility offered by building management or heating management systems may be incorporated to provide their usual sequencing, lead lag, rotation and other features. Although the description and drawings are based on two boilers being ganged to the header it should be understand that greater numbers of boilers or other heat emitters may be ganged together on the header. A single boiler may be advantageously incorporated on a header where it is known that some future project will require greater input thus allowing additional boilers to be added later. It should be understood that the headers may be prefabricated or in kit form, to speed site connection.

The invention will now be described by example with reference to the following drawings wherein: Drawing 1. is a diagrammatic representation of a higher level ganged header loop forming the present invention.

Drawing 2. is a diagrammatic representation of a low level ganged header loop forming the present invention.

Drawing 3. is a diagrammatic representation of high level ganged header loop forming the present invention as might be used with a cooker or other heat emitter requiring a vented gravity circuit.

Referring firstly to drawing 1. there is shown diagrammatically a ganged header loop (1) to which are adjoined boilers (2) via flow and return pipes (3) incorporating shunt pump and valves (4) also shown by way of example expansion safety system (5) auto air vent (6) main heating system pump and valves (7) zone valves (8) automatic bypass (9) and drain off (10). Drawing 2. shows diagrammatically a ganged header loop having similar components to that in drawing 1. but with the header at low level and having the addition of gravity check valve (11) to prevent heated water in the header circulating through any boiler that is off.

Drawing 3. shows diagrammatically a ganged header loop having similar components to that shown in drawing 1. as would be applied to a cooker or heat emitter wherein the cooker/heat emitter requires a gravity or thermo-siphonic circuit to dissipate heat from its water jacket showing in addition to similarly numbered components on drawing 1. a cooker (12) a cylinder (13) a heat leak radiator (14) together with a feed and expansion tank (15). In this system the header in addition to providing a neutral point for gravity dissipation of heat from the cooker to the header enabling such heat to be drawn around the main heating system by the heating

pump (7) and/or to provide heat by gravity circulation from the header to the cylinder (13) and the heat leak radiator (14) this heat being sourced either and/or by cooker or boiler.

When the heating system is first activated by the controls (not shown) or when other full load conditions prevail all boilers together with their shunt pumps are actuated by their respective control thermostats or building management system controls (not shown) and heat is circulated to the ganged header loop (1) the main heating system pump (7) in turn circulates heat from the ganged header loop (1) via the zoning valves (8) to heat emitters (not shown). It should be understood that the zone valves (10) and the main circulating pump (7) could be substituted by zone pumps or other controls.

It should be further understood that where high resistance boilers or other circumstances dictate the boilers could be actuated by sensors or thermostats in the ganged header loop (1) to reduce thermal swing while the inbuilt boiler thermostats would act as temperature limit thermostats only. When the heating system heats up and/or part load conditions prevail causing the header temperature to exceed the lower thermostat setting of one or more of the lag boilers this will cause such boilers to close down leaving the lead boiler with its higher thermostat setting to carry the system load unless the system load increases to the point where the ganged header loop (1) and lag boiler temperatures drop actuating the lag boiler to assist in meeting the higher load.

Claims

CLAIMS 1. Means of linking a boiler or boilers to a single pipe of a loop header so that thermosyphonic action and or gravity check valves prevent heat flowing from the header to inactive boilers.
2. Means according to Claim 1 where the header is run above the boilers so that thermosyphonic action prevents heat flowing from the header to inactive boilers.
3. Means according to Claim 1 where the header is run below the boilers where thermosyphonic action would not prevent heat flowing from the header to inactive boilers such heat flow being instead prevented by gravity check valves.
4. Means according to Claim 1 or 2 where the loop header is used as a neutral point link for unswitchable heat source boilers or cooker/boiler/s and switchable heat source boilers or cooker/boilers.
5. Means as above in conjunction with the description and drawings accompanying.