Difference between revisions of "Central heating design"
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== Heat Emitters == | == Heat Emitters == | ||
| − | + | '''''Emitters''' are means of heating spaces, such as radiators, under-floor heating etc.'' | |
| − | + | ||
| − | * | + | === radiators === |
| − | + | ''output mostly via convection: heat air to heat fabric of room & its occupants'' | |
| − | * underfloor | + | |
| − | ** other radiant e.g. in wall, in ceiling (I kid you not!) | + | ==== output specifications ==== |
| + | * Delta-50 and Delta-60 | ||
| + | |||
| + | ==== locations ==== | ||
| + | * wrt heat losses - under windows v. inside walls | ||
| + | |||
| + | === fan-assisted e.g. kickspace === | ||
| + | ''forced convection'' | ||
| + | * particularly suitable for small rooms with limited wall space for rads (e.g. kitchen) or too-high heat-loss/floor-area ratio for UFH (e.g. bathroom) | ||
| + | * fast warm-up | ||
| + | * may feel uncomfortably cold when shut off by thermostat (like electric fan heaters) | ||
| + | |||
| + | === underfloor === | ||
| + | ''radiant: heat occupants and fabric directly'' | ||
| + | * more efficient (e.g. 20%?) than radiators | ||
| + | * more comfortable: warm feet, cool head; less stuffy | ||
| + | * better for heating large spaces e.g. halls | ||
| + | * limited heat output due to limitation on max confortable floor temperatures: may be insufficient for small rooms with large heat requirements & large losses e.g. bathrooms | ||
| + | * heat output dependant on floor covering | ||
| + | * slower to heat & cool than radiator based systems: need better control systems | ||
| + | * need radiant-sensing instead of conventional air-temperature-sensing thermostats? | ||
| + | * hydronic generally require lower water temp than rad systems - really need extra pump + thermostatic mixing valve to run off mainly rad-based system | ||
| + | * better suited to lower-temperature flows from condensing and renewable sources | ||
| + | * expensive & disruptive to retro-fit to existing building: need to remove & relay floors (or poss. ceilings below for upper-floor installations) | ||
| + | |||
| + | === other radiant === | ||
| + | e.g. in wall, in ceiling (I kid you not!) | ||
== Controls and Zoning == | == Controls and Zoning == | ||
Revision as of 00:27, 15 January 2007
This article is about designing and installing Central Heating systems.
Heat requirements
- Discuss + links to whole-house heatloss calculators
- Discuss + links to energy conservation articles
Heat Sources
- single source
- gas or oil boiler
Discuss types of boiler, combi/conventional choice etc asper Ed's Boiler Choice FAQ with additional discussion of- combined range+boilers
- CHP (Microgen, Whispergen)
- electric
- peak rate v. off-peak
- standalone electric boilers
- thermal store
- gas or oil boiler
- multiple sources
- sources (additional to above):
- ranges (Aga, Rayburn etc) with back boiler
- wood burner with back boiler
- solar thermal hydronic
- ground source heat pump
- combining sources:
- thermal store
- neutral-point mixing things
- controls
- sources (additional to above):
Heat Emitters
Emitters are means of heating spaces, such as radiators, under-floor heating etc.
radiators
output mostly via convection: heat air to heat fabric of room & its occupants
output specifications
- Delta-50 and Delta-60
locations
- wrt heat losses - under windows v. inside walls
fan-assisted e.g. kickspace
forced convection
- particularly suitable for small rooms with limited wall space for rads (e.g. kitchen) or too-high heat-loss/floor-area ratio for UFH (e.g. bathroom)
- fast warm-up
- may feel uncomfortably cold when shut off by thermostat (like electric fan heaters)
underfloor
radiant: heat occupants and fabric directly
- more efficient (e.g. 20%?) than radiators
- more comfortable: warm feet, cool head; less stuffy
- better for heating large spaces e.g. halls
- limited heat output due to limitation on max confortable floor temperatures: may be insufficient for small rooms with large heat requirements & large losses e.g. bathrooms
- heat output dependant on floor covering
- slower to heat & cool than radiator based systems: need better control systems
- need radiant-sensing instead of conventional air-temperature-sensing thermostats?
- hydronic generally require lower water temp than rad systems - really need extra pump + thermostatic mixing valve to run off mainly rad-based system
- better suited to lower-temperature flows from condensing and renewable sources
- expensive & disruptive to retro-fit to existing building: need to remove & relay floors (or poss. ceilings below for upper-floor installations)
other radiant
e.g. in wall, in ceiling (I kid you not!)
Controls and Zoning
- Zoning
- Y-plan, S-plan, pump-plan
- Timers, programmers, thermostats, programmable thermostats
- location of thermostats
- hall or living room - no external heat sources
- location of thermostats
- TRVs
- mixed rads + UFH layouts
- On/Off v. proportional control (aka Digital v. Analogue)
- Feedforward aka weather compensation etc
Pipework
pipework materials
plastic
barrier v. non-barrier
Conventional Wisdom is that only barrier pipe should be used for CH systems as the metallic barrier layer prevents oxygen diffusing throug the plastic walls of the pipe into the primary water and causing corrosion in ferrous and possibly other metallic parts of the system - boilers, radiators etc. However Hepworth Plumbing Products have stated [[1]] [[2]] in the uk-d-i-y newsgroup that:
If Hep2O Standard pipe has been installed in accordance with our instructions in a central heating system and one of the recommended inhibitors used there is no technical reason why it should not continue to give good service for many decades.
and
It is now considered by British Gas that central heating systems that include plastics pipe manufactured to the appropriate British Standard (such as Hep2O) do not represent a potential corrosion problem from oxygen ingress where the system water includes an adequate strength of inhibitor. This applies equally to Barrier and Non-Barrier pipes.
copper
pipework layout
pipe sizes v. heat-carrying capacities + noise
microbore
easy install + balancing
tree + branch
([28]-22-15-[10/8]) - good for balancing
dual loop
inherently balanced but rarely practicable
random
bad for balancing but sometimes necessary
Installation
- routing
- installation in solid floor
- joist notching
- drain-off points
- plastic v. copper or chromed pipetails
- play in tails
- pressure testing
- flushing