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In economics, demand is the quantity of a good that consumers are willing and able to purchase at various prices during a given period of time. The relationship between price and quantity demand is also called the demand curve. Demand for a specific item is a function of an item's perceived necessity, price, perceived quality, convenience, available alternatives, purchasers' disposable income and tastes, and many other options.

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  1. M

    URGENT Heatslave 12/14 No Hot Water (for a week now). :-(

    Hi all. I have a 20 year old Worcester Bosch Heatslave 12/14 Oil-fired I'm getting about 20 seconds of hot water, then the boiler won't fire. I can crank the HW dial right up and it'll fire and give me another 20 secs of hot water. It won't fire again with demand from the tap. It was losing...
  2. L

    Worcester Bosch FS 30 CDI not coming on demand for heat

    HI All, Weird problem with an FS30 CDI, The boiler does not come on when demand for heat (LR terminal) is on, but I can turn it on manually via the service menu. Heating controls all seem fine, but anyone seen an issue before where it doesn't seem to register the demand for heat and just stays...
  3. A

    Vailant Turbomax Restarting on hot water demand - any clues?

    Hi, I have a 20yr+ old Vaillant Turbomax VUW 282 with a magaclean (on the flow side) and connected to Hive system for a 4 bed house. Had it serviced by British Gas engineers - but its a mixed bunch that come around and often depends on the engineer quality. Recently had its diverter valve...
  4. theboyroberts

    Logic Combi ESP1 35 always showing demand for Central heating

    Hi folks, I've got a potential problem with my Logic Combi ESP1 35. When the boiler is set to Central Heating and Hot water mode, the boiler indicates that there is a constant Demand for Central heating. When the thermostats (TP5000 Si) are turned off (both pulled from the wall and also...
  5. A

    Shower pump activating for a few seconds when no demand

    Hi everyone. I recently had to replace my shower pump and increase the size of the cold water storage. Since moving to a gravity fed pump the pump is activating with no demand for a few seconds. The pump is now connected to all outlets in the house but I am concerned it will burn out if it...
  6. A

    Gledhill Unvented Cylinder Loud Bang Hot Water Demand

    Recently had a new heating and hot water system retrofitted in a domestic property. Previous hot water system was gravity fed with a vented cylinder. New system as shown in the photos. Installer commissioned system about 3 months ago and all was working fine. There have since been two faults...
  7. J

    Electric on demand water heater advice

    I'm in the process of buying a property which needs a complete bathroom overhaul. The current bathroom has an electrically powered hot water tank feeding a bath, shower and sink. I would really like to remove the water tank to save valuable space (and probably energy usage too) and so wondering...
  8. M

    Sizing a boiler for heating demand

    Is the usual way of sizing the boiler for a C/H system to add up the kW of all the required radiators. Then add 10% for heat loss in the pipework? I know how to do it with regards to a combi and the flow rate rate required in litres per minute with a 35 degree rise in temperature. Thanks.
  9. CorgiDirect

    Extended due to popular demand - 30% off CP12 landlord pads

    Extended due to popular demand, 30% off CP12 pads View here - Landlord Gas Safety Pads CP12 - https://www.corgi-direct.com/landlord-gas-safety-pads-cp12-17950-3421009
  10. I

    Boilder and pump keep running when demand has stopped

    Hi all, hopefully someone can offer some advice: I have a potterton profile 80 boilder (I know quite old!). It's a S-PLAN system. Over the last few months, the boiler control has been a little eractic, but I have struggled to nail it down. Lately, it's now been running all the time (pump...
  11. P

    Boiler over-temp and cuts out on low heat demand

    Hi all. I have a large house (ex commercial building) It's heated by 2x Clyde Combustion CM-1 boilers rated at 220,000 btu each. When the whole building is being heated, they work fine (although the fuel oil bill is ruinous) My problem is - 70% of the building is currently being renovated and...
  12. B

    Boiler fires up on HW demand but not on CH demand.

    Hi I have a fully pumped system. CH hasn't been used since April. Last Friday was a bit chilly so I turned the room stat up but the boiler didn't fire up. Boiler works when I demand HW. I installed a new room stat (Drayton RTS8) which made no difference. I then changed the controller from a...
  13. B

    Glow Worm boiler keeps cycling with no demand

    Hi all, first post but have a major issue that's causing me headaches. My system boiler (Glow Worm Flexicom 18hx) continues to cycle to keep itself up to temperature, even without any demand from the programmer (Drayton Lifestyle LP 522) which is also causing the pump in the upstairs airing...
  14. M

    Ideal Independent C30 CH coming on when no demand

    Sorry if this is a load of daftness - I've not a clue about heating systems! Not long moved and the house has its got an Ideal Independent C30 boiler. Issue I'm having is the CH turns on quite regularly even when the thermostat is much lower than the house temp (set to 15°C and house temp is...
  15. F

    Grohtherm 3000 (19665) - Boiler not recognising demand for hot water

    When attempting to use the shower our combi-boiler does not fire up in response to the demand for hot water. However, if using the Exafill to run water into the bath then the boiler DOES fire up - as it does also with other hot taps in the house. British Gas service engineer has checked the...
  16. T

    Should Ideal Logic Combi ESP1 35 show demand for heat when thermostat esrpt4 doesn't need it?

    Hi all, I've just moved in to a new build with the above boiler and two thermostats (one upstairs, one downstairs). The other day we had an issue where the heating upstairs stayed on no matter what the thermostat said, I managed to factory reset the upstairs thermostat and since then the rads...
  17. C

    Opinion request on hot water demand

    Looking at something like a megaflo unvented, typically you heat this to 65 degrees. Most of the day, I have hot water sitting in the tank not being used, and if I do not draw any off, the insulation is very good and keeps it at 65 degrees. If I draw hot water from the tank it gets colder as...
  18. M

    Grant Vortex Combi 21e Constant Demand

    Hi Folks, I'm new on here and this is my first post. I have one of the Grant combis, and wish I'd never had it fitted :disappointed: The latest one is no hot water :disappointed: I've noticed over the last few weeks that the temperature of the hot seems to be hot to start with, and then...
  19. K

    Unvented hot water system noise when hot water demand is made

    Hi all, Ready for War and Peace ? Hope you are all sitting comfortably, so let me begin...p.s. I am not a plumber, I work in IT so sorry if incorrect or wrong terms used ! We have a unvented hot water system, installed in Jan 2014. FlowMaster cylinder; Zilmet 11H HY-PRO (18ltr / 3bar...
  20. W

    Glowworm Energysaver - always on / reporting demand

    Hi! I can't find another post on the same subject but apologies if I have missed one. i moved house last November and soon after had a free BG boiler service which reported no problems. recently we had a surprisingly large gas bill and it got me thinking: * the boiler is in the attic above the...