Changing to Combi or Condenser: any benefits?

[darkan9el]

Hi all, I've recently bought a house and I'm going to refurb the bathroom and while I'm at it I thought I would change the boiler... no not the girlfriend. the heater thing lol!

At the moment I have a back boiler with a bog standard gas fire sat in front of it in the lounge. I had a gas leak recently; the pipe was not covered and ran through some rubble, this caused the pipe to corrode and cause the leak. I had it sorted quickly but shudder to think what might have happened. I had the system checked over and was given the all clear. The heating not surprisingly now works much better and the water actually gets hot.

I had a combi boiler in my previous house but it came with the house, I liked the convenience and economy of it so I want one here too.

The timer is a Randall 3022; very basic. I have 8 rads, 3 of which are large single rads, the rest are smaller doubles. The fire is a Baxi PW5 deluxe.

As well as heating the house and water, I want to run a shower off the new boiler, but not sure whether this is feasible because we have low pressure on the system due to the new Kingsmill hospital being built nearby. Prior to them starting we had medium to high pressure.

Any Advice would be helpful

 

[simond]

You DID say any advice?

My advice would be to get 3 quotes. Anyone that does not get their flow cup out to measure the water flow should be discounted as a chancer, if you are asking for the suitability of a combi.

If the standing pressure is above a bar then you could partition yourself a reliable water flow rate by adding an accumulator to a combi; this would cost extra and the necessity of using one depends on how bad the fluctuations are.

 

[corgiman]

BTW you get condensing COMBIS and condensing CONVENTIONAL boilers

 

[darkan9el]

Ok well the first thing is to get the pressure tested, so i know what i'm working with.

Corgiman: Well thats something new I've learned, are there any advantages to having a combi condenser over a straight combi?

tia

 

[corgiman]

you probably cannot have a non condensing combi anymore

unless you get an approved person to carry out a survey and excempt you from Part L of the building regs

other than that they are more efficient

 

[Agile]

Ok well the first thing is to get the pressure tested, so i know what i'm working with.

As stated its the FLOW rate that you have to test !!! At a mains supplied tap like the kitchen or outdoor tap or better both together and added up.

You can do that yourself with a stopwatch or second hand and a bucket of measured capacity. Then a little pre GCSE mats and you have the flow rate in litres per minute.

The minimum to have a good system would be about 16 li/min open pipe but 20 or more would be good.

The professional way is to measure the dynamic flow. Thats the flow rate whilst say 0.5 bar residual pressure is left in the pipework as thats needed by most showers and a combi has a flow resistance to be overcome.

Tony

 

[gas4you]

Most new combi manufacturers state that a minimum of 0.5 bar cold mains pressure is required to get full flow through the boiler. I don't know if I believe there findings, but hey ho I'm only a lowly installer

 

[bengasman]

Chances are that the water company will improve the pumps if the pressure drops that low. At 0.5 bar the hospital will have a problem unless the whole thing is on ground floor level. Combis will work at the minimum pressure but will not produce all the hot water they should according to the spec. when you change a back boiler to a condensing combi, and do all the proper things with timers, roomstat and trvs, you may be able to cut your gas bill nearly in half, provided you keep the house at the same temperature it is now and at the same times on and off. In reality you will probably keep the house warmer and over a longer period per day. Still cheaper than what it was and more comfortable. Chances you will be able to legally get a non condensing boiler installed are pretty slim. I don’t see why you would want a conventional boiler as the price difference is small.

 

[darkan9el]

Hi I'm back... been a bit busy with work blah blah! Thanks for all the advice so far it is really helping me understand all this.

I turned a few stops, they started leaking so replaced them and now water pressure is fine.

I don't want a conventional boiler I want a combi and if it's a condensing boiler much the better. I also want a shower unit to go with the combi and will run from the combi.

What I want is some advice on which boiler to get based on reliability, quality and features. and a good quality shower unit.

I have a good corgi guy who will fit the boiler, but I've been reading a few posts here and some are better than others.

Regards Lee

As a side note: I also want to ask about the PARVA HE boilers and the SABLE HE boilers are they any good?