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Central Heating

System vs combi boiler for 4 bedroom, 2 bath house - rental property with working professionals

Anonymous user 09/03/2024 - 2.56 PM

Hi. I am renovating a house to rent out rooms to working professionals (i.e. shared house). There will be 4 bedrooms, two bathrooms and gas central heating. The tenants are likely to be working professionals so they will probably be using the showers at the same time in the mornings. I am therefore looking for the best option to ensure there will be hot water. At the moment the house has a Vaillant ecoTec Pro 24 combi boiler. From what I've read it doesn't look like this boiler will be powerful enough for what I want. Since the diverter valve is defective and needs to be replaced anyway, I am simply thinking of getting a new boiler - either Vaillant or Worcester. I've read that combi boilers will not be powerful enough to heat water for two showers running at the same time. Is this really true, even if you get a very powerful model? I have read that a system boiler is better when you need two showers running at the same time, but the problem is that the hot water is limited by the size of the tank. Given that there could be 4 people showering in quick succession, I am worried that the hot water would quickly run out, especially since space is at a premium in my house. Any tank would need to fit under the boiler as that is the only space I have available, unless it is possible to store the tank outside somewhere (the boiler is on an outside wall). Something else to bear in mind: there is scope to convert the loft to add an extra two bedrooms and a bathroom. I am not sure if I will do this (can't afford it right now!) but if I do I would prefer not to have to replace the boiler. Would a system boiler be more future proof, even with a limited tank size? In summary, I would much prefer to have a combi boiler, but if that really isn't feasible for my needs then I would get a system boiler and try to fit the hot water tank in... Please let me know your thoughts and if you recommend any particular models. Thanks for the help!

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4 Answers

Griffiths Plumbing & Heating

No reviews yet

Bristol

Hiya If you did fit a combi the pressure with defiantly drop when both showers are being ran at the same time. If you do ever add the third bathroom you would be getting complains from the tennets I'm sure as the problem would only get worst. A system boiler would be your best bet. Vaillant do a good range of system boilers you would be needing about a 30kw. The unvented cylinder wants to be around 210 litres in size. Good luck trying to fit it all in!!!

Answered26 April 2018

T Services

Rating: 5 out of 5

Eastbourne

i would opt for a system boiler myself... a 140litre cylinder to keep the size down but with twin coil for faster heat recovery. try not to oversize the boiler tho to keep the efficiency high. probs would get away with a 15kw or 18kw depending how many rads you have.

Answered27 April 2018

Instant Plumbing and Heating

Rating: 5 out of 5

Chorley

Hi You don't state what your water pressure is, or flowing at i.e. litres per minute, if your water flow is great say around 18Lpm then consider one of these VITODENS 222-F it is a combi and has a built in cylinder which can be up to 130 Litres in capacity, comparable to a seperate 350 litre cylinder. Other manufacturers do similar boilers that can supply up to 22 Lpm Glowworm Worcester etc. Thanks Phil

Answered12 June 2018

Simple Plumbing Solutions.

Rating: 5 out of 5

Ferndale

Maybe fit a Worcester 8000 style 50 kw combi 18 ltr a min ? And in the attic put a electric shower in .

Answered31 March 2021