Combi boiler?

Nicholas

No-one has yet mentioned that a combi can only do one thing at a time, and I believe they prioritise the hot water. This means that if you are filling your bath on a bone chilling day the radiators will go cold!

It's swings and roundabouts really. A combi is better in the summer when the central heating is not needed anyway, and the water at the mains is relatively warm. But in the winter when the mains water can be between 3-5C, it has its work cut out trying to heat the water to the required temperature.

moneysavingplumber

shrewdal wrote:

Although I have to say that not much can go wrong with the combi,

A thousand heating engineers just shouted 'nooooo!!!'

They are far more complex than conventional boilers and further complicated by the fact that so many of the necessary components that would usually be found elsewhere on a heating system are crammed into the combi's own casing. These will include an expansion vessel, divertor valve and diaphragm, plate heat exchanger and possibly a heat store unit, auto and manual air vents, pressure relief valve, flow switches, thermistors and sensors. Add to this all the usual boiler components like the fan, air switch, PCB, wiring looms and gas control valve and there is an awful lot that can go wrong.

They are alot more easy to diagnose and repair than they used to be and more manufacturers now include fault-coded neon signals.

Woby_Tide

Nicholas wrote:

No-one has yet mentioned that a combi can only do one thing at a time, and I believe they prioritise the hot water. This means that if you are filling your bath on a bone chilling day the radiators will go cold!

If you find that then there is something wrong with your boiler/your radiators or both, the time it takes to fill a bath is negligible. If the radiators can go cold that quickly then the heat setting is probably wrong.

If you get a decent boiler in the first place I've found ours fills the bath at just as quick a rate as any header tank I've used can. Also on mains pressure inflow so it pretty much provides us with a power shower without needing any pumps or other equipment. The majority of electric showers I've used in recent times come nowehere near as close to it.

rizla01

One point that no-one has mentioned (And the only point in favour of a combi IMHO) is that you can DRINK the hot water straight from the tap or use it to cover spuds Etc prior to boiling and so saving a few quid.

The reason that you cannot drink from conventional systems is cos it's stored and dead birds fall into storage tank, Etc but a combi is no more than a sophisticated kettle.

MyUserNamesTaken

Personally, I prefer my combi. It replaced a solid fuel boiler system and immersion heater. I have an attic room, so no space for a header tank (also, the attic room would have had to lose its rad, as the header tank must be higher than the highest rad in the house!). The immersion tank took up too much room in the spare bedroom. I've got a vaillant ecomax boiler and it's great!

alanobrien

frugglewump wrote:

Yep that makes sense - and I have now googled and the diagrams etc make sense as well. I can see the advantages wrt storage - but no idea about gas bill.

Anyone on here switched from traditional to combi able to comment?

For what its worth we switched from a combi back to a traditional boiler mostly because of the low flow hot water rate issues with the combi and secondly because i like the idea of the back up emmersion heater.

Never regretted that decision.........

Nicholas

Woby_Tide wrote:

If you find that then there is something wrong with your boiler/your radiators or both, the time it takes to fill a bath is negligible. If the radiators can go cold that quickly then the heat setting is probably wrong.

If you get a decent boiler in the first place I've found ours fills the bath at just as quick a rate as any header tank I've used can. Also on mains pressure inflow so it pretty much provides us with a power shower without needing any pumps or other equipment. The majority of electric showers I've used in recent times come nowehere near as close to it.

This is only something I read on the internet re the pros and cons of a combi. I have recently moved from a house where I had a separate multi-point water heater (instantaneous) and central heating system.

When we moved, had a new system put in, and decided to go for a separate hot water tank. Have not yet regretted the decision......

moneysavingplumber

rizla01 wrote:

The reason that you cannot drink from conventional systems is cos it's stored and dead birds fall into storage tank, Etc but a combi is no more than a sophisticated kettle.

Ahh the old 'dead bird/rat in the storage tank' chestnut :rotfl:. I hear this all the time, from customers that is, but in twenty years I've never once found one in a storage tank, and feel left out because of it! I don't know anybody else that has found one either. If stored water is installed correctly with the WRAC kit then it will be insulated, fitted with a tight fitting lid, ventilated, and there will be mesh filters in the overflow and ventilation to prevent insects entering the tank.

Furthermore, any water that has been treated by either filtration or heat process after entering the property cannot be classed as drinking water, it has to be exactly as it comes via the main. Not that I wouldn't eat spuds that had had hot water from the combi poured onto them, but if I'm working in a house and I've turned the water main off, then I'm happy for the client to make me a tea via the hot stored water, just as long as I've checked the tank for dead birds first :rotfl: .