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A gas heater is a space heater used to heat a room or outdoor area by burning natural gas, liquefied petroleum gas, propane or butane.
Indoor household gas heaters can be broadly categorized in one of two ways: flued or non-flued, or vented and unvented.

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  1. dave100

    New unvented cylinder / Replace old vented cylinder and add a ST pump?

    Hello, I am renovating a small bathroom in an apartment on the 5th floor. Heating is electric, no gas or oil. I have four (related) questions about this below. I had intended to reuse the cold water tank and the cylinder sitting underneath it but my plumber suggested I replace the cylinder as...
  2. M

    Unvented cylinder install query??

    Hi guys. Is there any reason you can’t can’t downsize the hot water draw off from 22mm to 15mm straight away? Other than the flow rate being affected would there be any other concerns? Cheers
  3. M

    Heat pump unvented install balanced cold

    If changing a combi boiler system to a heat pump. What do they usually do with the balanced cold connection on the hot water cylinder? Cap it. And put a pressure reducer on the mains so they have equal hot and cold pressures? I can't see them repiping a balanced cold from the cylinder to each...
  4. T

    Unvented Expansion Vessel Replacement - what else needs changing

    Potable water unvented expansion vessel needs replacing - water is coming down the tundish. What else needs to be replaced. Does the enginneer need a G3 unvented certificate to do this work and what are the consequences if he does not have one
  5. S

    Unvented Tank Advice Please

    Hi. I have looked at similar posts but not seen exactly what I'm after ... unvented Gledhill 200l fitted a few months ago. A few weeks after and since most times when we turn on hot water tap in the morning there is a long groaning sound (I have a recording if it helps). Have contacted...
  6. N

    Unvented cylinder size

    200/210 or 250l indirect unvented cylinder... Pros and cons of both please guys, whats the thinking?? Better to go bigger, or are there other considerations to be thought of....?
  7. D

    Efficient way to heat radiators and unvented cylinder

    I have a gas boiler heating radiators and also heating an unvented cylinder. I have a Honeywell programmer which has the water heating up 1.5 hours early morning 30 mins midday and 2 hours evening The heating is on a couple of times a day. With the energy prices I am wanted to ask if hearing...
  8. A

    Plumber Qualifications Query

    Hi. I have an elderly neighbour getting quotes who has asked for my help and opinion, I don't really have a good one as it is not my area of expertise but I am trying to help. The quotes are all similar prices but She seemed to like one person and quote more than the others and I noticed that...
  9. J

    Unvented cylinder recommendations?

    Hi all, I'm due to install my first unvented cylinder. (I've had my unvented ticket for several years, but not actually done a brand new unvented install yet). It's a house renovation, with a new hw and heating system. The house currently has an old gravity floor boiler, that will be coming...
  10. D

    Unvented water heater advise

    Been to a site today and every sink has a 15l water heater underneath on each of the prv's discharge after the tundish their is only about 200mm of 22mm copper before it enters the sink waste below each sink been like this 10+ years their is no other pipework local to each and most of the...
  11. J

    unvented cylinder v combi store

    Hi all, My customer is renovating a house. Complete renovation of the plumbing. It's a three-bed house for a young family of 3. It will have one main bathroom (bath and maybe an over-bath shower), plus two shower ensuites. I have yet to check the incoming water pressures/flow rates to the...
  12. Fogster74

    Working on heating side of system with an unvented cylinder, no G3?

    Hi all, I'm a competent DIYer with an engineering background and am active in Heritage Buildings. I never touch anything I'm not allowed to albeit I've worked on the wet side of my own heating on the central heating circuit before when I had a combi - balancing rads, add a Fernox TF1, washing...
  13. C

    Humming from unvented cylinder

    Hopefully someone can point me in the right direction. Before I start I am G3 qualified. As per usual I was asked to rectify a leak on a combination valve. I installed a like for like 3.5 bar valve, all good, however I I checked pressure in exp vessel to find no pressure at all (Never been...
  14. R

    Unvented Hot Water System

    Hi, I’ve purchased a new build property and had a few issues with the unvented hot water system. I’ve now asked the developer, builder and plumber for proof of G3 certificate of the plumbers but have been told they have no need to show me this. I’ve searched the gas safe register and it’s not...
  15. B

    Unvented cylinder won't stop heating up when CH is turned on

    I have recently moved into a house with the following heating system: Traditional boiler (Worcester Greenstar Ri 24 with only one temperature dial and no pressure gauge) Vented central heating (cold tank in loft) Unvented hot water (Excelsior cylinder with pressure gauge plus white expansion...
  16. gingalig

    Unvented and boiler heat loss calcs

    I have a house with 14kw heat loss using the whole house method, ( Navien oil system boiler ) I aimed to use heat engineer software on acceptance of the quote but have been struck down with covid, the unvented cylinder is 300ltr due too a family from Ukraine living there ( 8 people living...
  17. J


    Hi All, looking for some advice. I have ARISTON CLASSICO UNVENTED INDIRECT CYLINDER ST1 210 which has corroded at one of the main inlets and is leaking water when in operation. This unit is now obsolete and need to source a replacement. Obviously I am aware that I cannot replace the unit myself...
  18. P

    Unvented cylinder wiring

    Hello all I'm replacing 2 unvented cylinder a which are (a) end of life and (b) installed in a way which is clearly not right (no 2 port shut off valve on the heating coils just for a start, and there are other issues). The heating coils are currently controlled with 3 port valves that are...
  19. M

    Re newing G3 unvented

    Has anyone recently renewed there unvented? Is the theory a long exam?
  20. B

    installation of Boiler - Unvented tank

    As part of a rebuild (added 1st floor to bungalow and extended back) we have removed every piece of plumbing and electrics, during COVID In preparation for the complicated stuff, during the build we have ... Gledhill unvented tank (preplumbed) placed in 1st floor airing cupboard New...
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