Should I go Combi or jst add a CH boiler?

[BigE]

Hi, new to the Forum an ex-boatbuilder not a plumber so hoping for some words of experience. Soon to move into a 1890s 5 bed detached in Southport with two bathrooms and no central heating, just gas fires and gas boiler for hot water, that boiler may be just a couple of years old. I have been advised to replace it with a combi, I'd prefer to add a simple, nice quiet, reliable boiler (if there is such a thing) in the cellar to manage central heating alone. I used to be a keen DIYer but I'd prefer to leave things to a professional these days, any advice is much appreciated.

 

[Puddle]

imho you are moving into to big a property to think combi,would go the system boiler, pressurised cylinder route if you have to main cold pressure for it ,if not maybe tank,open vented cylinder and pumped power showers
Do not listen to any one trying to push a combi on you,they are looking for the easy option

 

[erj]

boiler and cylinder, two bathrooms a combi is not going to cope very well.

 

[unguided1]

as said, system boiler and unvented cylinder is the best way to go

 

[SafeGasInstall]

as above ,system boiler and unvented cylinder ,or heat only with vented cylinder with expansive pump to bust the supply ,

need a free quote go to my web and fill the contact me form to get free of charge consultation and obligation free quote for the system upgrade

 

[BigE]

Thanks for all the advice, looks like its unanimous, I had a feeling a combi was an easy option for the installer, from reading this forum and web searching I suspect something like Valiant Ecotec Plus 637 or Worcester 30 CDI will be a good chice but I will take advice on that when I have found the right installer, I will have access to the house in a few weeks so it will wait till than, thanks again.

 

[GQuigley67]

its imporetant to get your mains pressure checked first to see if it will be enough for unvented system, a good installer should do this for you.

 

[BigE]

Good point, I will make sure that's done, I will also need to check existing water heating boiler to see if I can leave the hot water side as is initially with the option of changing to the new boiler if and when the old one gives up, or maybe go the whole hog and ditch the existing.

 

[AWheating]

your boiler size will depend on what output you need, any good engineer will advise you of this when he sizes your radiator and cylinder requirements.

 

[capitanpugwash]

You could of course have a combi if it's in your cellar, using the direct hot water to provide water for downstairs cloakroom/kitchen. You could then have open vented hot water using powered shower pumps or a thermal store and set up zones on the heating side. One of the zone valves could be set up with a programmer and cylinder stat to heat the hot water as if it was a zone. I'm guessing your house is larger than 150 sqm so would require zoning anyway. Set up 3 zones for example- downstairs, upstairs, water cylinder. Great advantage if you want solar cylinder/thermal store as you will want this on your 2nd floor near to the panels. When you turn on the kitchen sink or the cloakroom you will not have to wait for water from loft or set up a recirculation system. 24 hours a day you will get quick hot water from the combi size of your boiler. Good for larger properties. I've got exactly this set up with an Id**l boiler (don't tell gas man) and it's worked faultlessly for 3 years.

 

[Mrs Tara Plumbi]

Thanks for all the advice, looks like its unanimous, I had a feeling a combi was an easy option for the installer, from reading this forum and web searching I suspect something like Valiant Ecotec Plus 637 or Worcester 30 CDI will be a good chice but I will take advice on that when I have found the right installer, I will have access to the house in a few weeks so it will wait till than, thanks again.

I agree with the replies by the others, even though I love having a combi myself and to be honest if it were my house I would have a combi if possible.
In this blog post I listed most of the combis which claim to be good enough for big houses with two bathrooms: Tara Heating and Plumbing in Thanet, east kent: Looking for Combi for Large House with Two Bathrooms?
and this is the list:

• Worcester-Bosch Greenstar combi CDi wall mounted with 30 kw heat output and delivers 15.2 lpm or 17.2 lpm of hot water depending on model.
• For greater hot water flow rates you need the floor standing Greenstar Highflow heat output of 29 or 30 kw and 20 or 25 lpm.

• Vaillant EcoTEC Plus, heat output 28 kw, 20 lpm.
• Alpha CD50 Storage Combi holds 52 litres of stored hot water and delivers 18 lmp. Alpha boilers come with a five year manufacturers' warranty.
• Viessmann Vitodens 222-F combi delivers 20 litre of hot water per minute

There are probably some others.

 

[stevetheplumber]

You could of course have a combi if it's in your cellar, using the direct hot water to provide water for downstairs cloakroom/kitchen. You could then have open vented hot water using powered shower pumps or a thermal store and set up zones on the heating side. One of the zone valves could be set up with a programmer and cylinder stat to heat the hot water as if it was a zone. I'm guessing your house is larger than 150 sqm so would require zoning anyway. Set up 3 zones for example- downstairs, upstairs, water cylinder. Great advantage if you want solar cylinder/thermal store as you will want this on your 2nd floor near to the panels. When you turn on the kitchen sink or the cloakroom you will not have to wait for water from loft or set up a recirculation system. 24 hours a day you will get quick hot water from the combi size of your boiler. Good for larger properties. I've got exactly this set up with an Id**l boiler (don't tell gas man) and it's worked faultlessly for 3 years.

ive often used this system on larger properties but use the direct side for showers which saves having a pump for the showers a bit extra work if using a tank fed system for everything else as you need mains cold to the showers as well
a lot of customers have told me that using this system they dont have to put the hot water for mornings as like most people they only shower in the mornings so saves energy as well
also due to price wars in combis they are often cheaper than the equivlent system boiler

 

[BigE]

Pleased I found this forum, good advice, finally moving in to the house next week, I would like to keep existing Combi for hot water if it is not too old, not sure how effective it is for showers yet, with new system boiler for heating, now all I need is to find central heating engineer to give me a quote for full heating installation in Southport, but I think maybe these forums are not for promoting business but yellow pages is a bit hit and miss, any recommendations will be welcomed.

 

[SafeGasInstall]

Yes , please list your location and some one will be in contact With you ! We have a list of registered busineses here !

 

[stevetheplumber]

does zoning apply to retrofits of just new builds?

 

[GQuigley67]

anyone on here from southport could give him a quote ?

 

[doitmyself]

Soon to move into a 1890s 5 bed detached in Southport with two bathrooms and no central heating

Definitely a System Boiler and a vented or unvented cylinder (depending on water flow rates and pressure).

You need to improve the insulation as much as possible - loft and cavity (if it's not a house with solid walls). Check out Energy Savings Trust Grant Search

Also use the Boiler Size Calculator to find out what size system boiler you need. It's probably advisable to buy one slightly (10-15%) larger, so you have some spare capacity for the very cold winters we are getting at the moment.

You also need to get the correct size rads in each room. You can either rely on the installer to use his "experience" or use a rad calculator such as Stelrad Stars.

The actual rad used should be about 20% larger than the calculator suggests. This will allow the boiler to run with a 20 degree temperature difference between flow and return, which is more efficient as the return temperature will be at or below 55C, the temperature at which condensing begins.

 

[Heating-eng]

imho you are moving into to big a property to think combi,would go the system boiler, pressurised cylinder route if you have to main cold pressure for it ,if not maybe tank,open vented cylinder and pumped power showersDo not listen to any one trying to push a combi on you,they are looking for the easy option

You could also fit something like a wb 550cdi which gives around 23 l/m