Oil Combi Boilers?

Alfster

Hi,

Anyone offer any advice on how good oil combi boilers are? We have a standard Grant oil boiler  with a vented tank. It works well but there quite a few downsides I would love to get rid of:

> The cyclinder takes up a lot of room in the bathroom. 

> The loft space is too small to house cold water header tanks so they are also stored in the bathroom. Not only does this take up even more space but it means the cold water tap flow rates upstairs are so incredibly low. To the point that they don't even meet the minimum flow rate to activate booster pumps! 

> Pumps are also required for the main bathroom shower and en suite shower. 

Th other option is to go for an unvented tank but there isn't really a good place to put it in terms of the emergency relief valve. It would also still take up a lot of space still. 

We have a 5 bedroom house which is about 200 sqr mtrs. One main bathroom and a small ensuite. I would say the heating demands in the winter are quite large but the hot water demand for showers, baths etc is fairly low relative to the size of the house. Moreoever, we only have one main bathroom. 

If it woud work well any ideas on manufacturers, models etc? Thanks 

FreeBear

Alfster said: If it would work well any ideas on manufacturers, models etc? Thanks 

I would normally advocate looking at a heat pump, but you'd still need space for a water tank.

For oil fired combi boilers, one name springs to mind - HRM Boilers. But at £3K+, they are not particularly cheap.

QrizB

Just as an aside, your cold taps could all be fed directly from the mains, at mains pressure. There's been no good reason to feed them from a CW storage tank since the middle of last century.

Reed_Richards

I think combi boilers have had their day. They were a good idea in the right circumstances although I used to have a combi boiler that worked very badly for me because the pipe runs were too long and I had to wait an age get get any hot water.  Anyway, now we are being asked to move away from burning fossil fuels and there is no such thing as a combi heat pump.

By the way, if your cylinder is in your bathroom I would have thought it would be very easy to have an emergency relief valve fed to a tundish which feeds any water to a drain.  That's' what I do in my bathroom, using a dry trap tundish.   

spannerzone

I have a Grant external combi 26e oil boiler since 2010 - I have to say it's been very unreliable on the whole, it is serviced regularly but has had many faults over those 14 years. ALso, as mentioned above, it takes a while to get hot water in the bathroom due to the distance the boiler is outside and into the bathroom, so you waste water, quite a lot over the years.
 
Off the top of my head it's had:
3 replacement expansion vessels
1 additional (internal) expansion vessel fitted by Grant after I left a scathing online review) this was to try reduce pressure issues on the central heating as the boiler doesn't have sufficient capacity for many situations. This didn't really help though.
2 flow switches
1 control panel PCB circuit board
1 pump
5 mains power switches (internal)
1 Oil pump (leaked) 

Now I get a qualitifed engineer to service this but some items I've replaced myself as I'm an elecrtical engineer and can sort out most of the electrical faults.

In the last year it's started to clog up a burn sensor and I have to go clean the sensor to make it fire up...the engineer can't figure this issue out.

Everyone I ask says Grant are excellent, but I concluded the issues with this external boiler is that it's very well inslated against the weather but gets too hot internally and cooks the components, the circuit board, the switches fail as they go brittle with the heat).So an external boiler means no oil stink inside the house and space saved but external considerations are a contributing factor to its unreliability, that I am sure.

Kiran

I used to have a Worcester Heatslave 26/32 oil combi which I swapped our for a heat only and an unvented cylinder. I did this so I could take advantage of solar thermal and excess PV generation. Appreciate that isn't what everyone is looking for, but in doing my research I saw how many different types of cylinder there were available to suit spaces. For example you can fit a horizontal cylinder in your loft space to make best use of the eaves which largely go unutilised. 

In terms of the combi boilers, they have small tanks which keep a supply of water hot so its not quite a traditional on demand system.