Combi v Conventional

fagun · 26 Aug 2006

We have an old (non-condensing) conventional boiler. We're getting some plumbing works done, and thought it's the right to replace the boiler fro energy efficiency and cost saving purposes. But we can't decide on combi v conventional. Looking for some advice as well as suggested models.

Relevant detaisl:
- 4 bedroom Semi
- Presently 1 bathroom with power shower
- Tanks and Pump currently in the loft
- New mains pipe into the house, but older pipes in the house
- Pressure seems Ok, but was a bit weak on the shower before we put the power shower in
- Looking to do a loft conversion, including adding a shower / toilet upstairs. We think that there'll be sufficient space, even with the tanks.

We like our power shower, so are worried that mains pressure won't be enough.

Grateful for any advice.

Thanks

weareleeds · 26 Aug 2006

If installed correctly & you have a good mains supply & you get a high kw rated combi you will find that your existing power shower will appear to be lame in comparison to a mains fed shower

ChrisR · 26 Aug 2006

Depends on the power shower - Aquallisa Aquastream gives 18l/min.
If you have a combi, make the loft shower an electric one for when the combi fails

bab · 26 Aug 2006

I would recomend fitting a 35kw Vailliant EcoMax combi supply only the new en-suit with the instant hot water from the boiler & keep the cylinder as well,Its no problem to heat the cylinder with the combi & both showers will be able to be run at the same time.Your loft conversion is the perfect reason for this system. You can use any boiler as long as the kw is high to give a very good shower. Fitted this system lots of time & customers are very happy, IT ALSO give's a back up with the immersion in the event of a boiler breakdown.

fagun · 27 Aug 2006

bab said:
I would recomend fitting a 35kw Vailliant EcoMax combi supply only the new en-suit with the instant hot water from the boiler & keep the cylinder as well,Its no problem to heat the cylinder with the combi & both showers will be able to be run at the same time.Your loft conversion is the perfect reason for this system. You can use any boiler as long as the kw is high to give a very good shower. Fitted this system lots of time & customers are very happy, IT ALSO give's a back up with the immersion in the event of a boiler breakdown.

Thanks for all the replys so far. I think what you're suggesting bab is to fit a combi, and connect it to our hot water tank. Then when we do the loft conversion (we're not doing it for a few years), connect the new shower directly to the combi. If that's correct, should I try and connect the other taps (eg in the kitchen) directly to the combi as well - so that the tank is only used for the existing shower/bath?

Is this economical? The main reason for considering putting a combi in is that we might save money (our plumber was talking about £200-£300 a year).

fagun · 27 Aug 2006

ChrisR said:
Depends on the power shower - Aquallisa Aquastream gives 18l/min.
If you have a combi, make the loft shower an electric one for when the combi fails

I think its one of those (its definitely an Aqualisa, not sure of the make. We're not at home at the moment, so I'll check tomorrow).

bab · 27 Aug 2006

Having two supplie's is a small luxury but they all come at a price . If u connect lots of outlets to the combi outlet then when ensuit showering takes place theres a risk of a poor supply to both. 35Kw give's a supply that can cope with 2 15mm demands but there is allways gona be a dip in flow rate.You have got to ask yourself what will be the demand to run both showers at once. Alternative is to fit the combi to supply upstairs & convert the boosted shower to an electric,but then your power shower pump is wasted & u get a shower with a performance that will pale by comparison to what u had before. If u know all the pro's & con's then its your choice. I find a lot of installers want quick in & out £££££££££££.rather than complicated systems.Its your money & house ,choose what suits u.

ChrisRoberts · 28 Aug 2006

The new vaillant ecoTech pro is much nicer than the ecomax.

Agile · 28 Aug 2006

If your cylinder is reasonably up to date then I would suggest a new 24 kW combi just supplying DHW to the new shower ( in the future if thats the case ) in the loft.

That will coincidentally be the cheapest option of all ! 24 kW is quite adequate for most showers when the flow rate taken by the shower is no more than about 9-10 li/min.

Tony

topgazza · 29 Aug 2006

I'm also looking to replace my old boiler with a new one. Similar problem but I have a presurised system, about 4 years old, but live in a very hard water area. Is a combi recommended for this type of water or am I better off with a condensing ?

Agile · 29 Aug 2006

You need a condensing boiler regardless of wether its a combi or system boiler.

Tony

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Combi v Conventional

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