Boiler setup for house with 3 showers and no room for a water tank.

Discussion in 'Plumbing and Central Heating' started by Flipjango, 19 Nov 2021.

  1. Flipjango

    Flipjango

    Joined:
    6 Jun 2011
    Messages:
    112
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    We're about to renovate our old house to rent it out. It will have three bathrooms when its finished. The house currently has a combi boiler, which I'm aware isn't great if two people want showers at the same time. This wasn't a problem for us living there but probably will be for tenants when there's 5 adults all trying to get ready for work in the mornings so I will have to make some changes to the current set up. There is no space for a hot water tank/megaflow anywhere in the house unless we put it in a bedroom (definitely not ideal) so I'm looking into other options than system boilers. As I see it, our choices are either a new storage combi boiler (which will be about £2000 plus installation), or changing at least 2 of the showers to electric showers (about £350 each plus installation). Our water pressure is good. I can't find out very much info about storage combi boilers anywhere so I'm struggling to work out whether this would be a good option and whether they would potentially cope with 3 showers and a dishwasher running at the same time (as a worst case scenario). I'd love to hear some thoughts on the options or whether there's another idea I've missed?
     
  2. Sponsored Links
  3. oldbutnotdead

    oldbutnotdead

    Joined:
    11 Jan 2013
    Messages:
    4,752
    Thanks Received:
    1,005
    Location:
    Durham
    Country:
    United Kingdom
    Dishwasher is a red herring- most only have a cold feed.
    Electric showers- bad idea, if this is an HMO with a single electric supply then 2 simultaneous electric showers would use most of the supply capacity, boiling a kettle at the same time cld take you over the 100A mark. Electric showers are pretty poor at the best of times.
    Any room in any of the bathrooms? You really need to make room- doesn't have to be 1 big cylinder, could be 2 or 3 smaller (150 l). Combi isn't a good solution for serving multiple independent inhabitants. You could use combi dhw for kitchen and washbasins and keep the tanked dhw for showers.
    How is billing going to work (or will the rent include bills)

    EDIT Don't forget required annual maintenance for pressurised dhw cylinders.
     
  4. Flipjango

    Flipjango

    Joined:
    6 Jun 2011
    Messages:
    112
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    Yes, Its an HMO. Billing will be included in the rent. Problem is that two of the three bathrooms are already fitted as they were there already, though they are both tiny so barely space for the bathroom fittings, never mind anything else, even if we did rip them out and start again. The new third downstairs shower room is miniscule so even worse. The current boiler is already in the cupboard under the stairs and there is no airing cupboard. At, best I can create a 60cmx60cm tall cupboard in the kitchen next to the boiler, but if my previous system boilers are anything to go by I'm guessing this isn't nearly big enough. Also the plumbing is already in across the whole house and carpets are already down so it'd be hard to install any new pipework to put it anywhere else. So unless I can fit a cylinder into the same cupboard as the boiler stacked one on top of the other, I can't see any option to go down this route.

    What is the most space efficient vertical system boiler with a single cylinder? Are there any that are stacked double decker, boiler over the cylinder?
     
  5. Madrab

    Madrab

    Joined:
    4 Oct 2012
    Messages:
    8,568
    Thanks Received:
    2,482
    Location:
    East Renfrewshire
    Country:
    United Kingdom
    Do you have attic space? They're not as good as vertical cylinders but you do get horizontal unvented cylinders, that coupled with water saving shower heads may be an option.

    I know it doesn't solve anything but TBH this should have been considered before any work started. The main plumbing system backbone is a first fix piece of work, retrofitting main system can lead to real problems in the future.

    There are a number of storage combi boiler options (Viessmann/Vaillant) but they aren't cheap and they do have limitations
     
  6. oldbutnotdead

    oldbutnotdead

    Joined:
    11 Jan 2013
    Messages:
    4,752
    Thanks Received:
    1,005
    Location:
    Durham
    Country:
    United Kingdom
    If your 600 x 600 space next to the boiler is 2000 or greater in height you've got room there (just) for a 300 litre cylinder or maybe more (more would be better). If you have no loft space for header tanks then go pressurised dhw. Boiler doesn't need to be massive- worth getting a fast recovery cylinder to cope with rapid replenishment. Have a look thru this forum for links to a (highly recommended) heating solutions bunch- think they charge £100 but they design a solution rather than throwing a box at the wall
     
    • Thanks Thanks x 1
  7. Flipjango

    Flipjango

    Joined:
    6 Jun 2011
    Messages:
    112
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    No work has started, but the house is already basically finished as it was our family home, we are just making a few changes to allow us to let it out as an HMO. So the plumbing was perfectly adequate for the way the house was previously used, and we never needed anything other than a combi, and the layout is already fixed with no space was ever allocated to a tank as we never needed it. There is no attic space - the loft has been converted into two bedrooms already.

    We really want to keep the house, but the only way we can afford to do that and cover the mortgage is to let all the bedrooms out, but that's one more person than ever lived in it before, hence needing the extra bathroom.

    Thanks, this is really helpful. We have nearly 3m ceiling heights, so can easily accommodate the height, its just the depth and width that's the problem. If we can integrate this with the existing combi that'd be even better. When I've had an unvented cylinder before in other houses the associated pipework has always been massive so I didn't think this was an option.
     
  8. old duffer

    old duffer

    Joined:
    16 Oct 2021
    Messages:
    62
    Thanks Received:
    4
    Country:
    United Kingdom
    very simple and cost effective solution..continuos water heater. Either 1 per shower (only cost around £350 per unit) or go for a commercial output unit @ around £2500.
     
    • Thanks Thanks x 1
  9. oldbutnotdead

    oldbutnotdead

    Joined:
    11 Jan 2013
    Messages:
    4,752
    Thanks Received:
    1,005
    Location:
    Durham
    Country:
    United Kingdom
    Can't find the link to that design outfit but there will be a way of doing it. Yes there's a fair bit of pipework associated with unvented cylinders but good design and installation will minimise the space occupied. Long as your existing boiler is fairly modern and in good condition it can stay, you may find it more cost effective (bearing in mind EPC numbers) to replace it as part of the hot water scheme (planned replacement will always be cheaper and can be designed rather than having to throw something in quick to keep the tenants warm)
     
  10. Sponsored Links
  11. Flipjango

    Flipjango

    Joined:
    6 Jun 2011
    Messages:
    112
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    Thanks @oldbutnotdead. Its a Worcester Bosch Greenstar Jr I think, about 10 years old. Not sure if this is old enough to replace but not new enough to be up to date either!
     
  12. OwainDIYer

    OwainDIYer

    Joined:
    5 May 2010
    Messages:
    4,559
    Thanks Received:
    699
    Location:
    Stirlingshire
    Country:
    United Kingdom
    I would definately have at least one electric shower. It gives tenants a back-up (and so can save you the cost of an emergency call-out) when the combi fails.
     
  13. Flipjango

    Flipjango

    Joined:
    6 Jun 2011
    Messages:
    112
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    That's a great idea @OwainDIYer, thanks
     
  14. MeldrewsMate

    MeldrewsMate

    Joined:
    27 Jan 2010
    Messages:
    1,118
    Thanks Received:
    280
    Location:
    Buckinghamshire, Darn Sarf
    Country:
    United Kingdom
    Have you considered using a 15 litre electric storage heater for each shower? These are the sort that are usually fitted under a sink and will normally have a 2kW or 3kW element fitted, thus reducing the peak demand when compared to 9kW electric showers. Combined with water saving shower heads and training of the tenants (!!!) you can easily get two 3 minute showers out of a single unit local to the shower....for those who will undoubtedly question, that's 15 litres @60C combined with 10 litres @12C to get 25 litres @about 42C; 25 litres @ 4 litre/minute = 6 minutes showering time.

    The education part is to train the tenant/user to turn the bloody shower off when they're soaping-up, or risk having to wash it off in colder water.
     
  15. Flipjango

    Flipjango

    Joined:
    6 Jun 2011
    Messages:
    112
    Thanks Received:
    0
    Location:
    London
    Country:
    United Kingdom
    Thanks, but I really don't think I can expect tenants paying their rent to have how they shower dictated to them. Its really not my place to tell them to have shorter showers. I think we'll probably just have to forgo one ensuite and have one combi and one electric shower instead.
     
  16. MeldrewsMate

    MeldrewsMate

    Joined:
    27 Jan 2010
    Messages:
    1,118
    Thanks Received:
    280
    Location:
    Buckinghamshire, Darn Sarf
    Country:
    United Kingdom
    Fairy-nuff, though if it were on a 200, 400, or 600 litre hot water cylinder they'd understand that when they'd used up all the hot water the shower would go cold....maybe my eco-energy-saving side is playing up.
     
  17. Harry Bloomfield

    Harry Bloomfield

    Joined:
    30 Dec 2018
    Messages:
    9,613
    Thanks Received:
    1,298
    Country:
    United Kingdom
    Two electric showers would be too much load on the system and one should work well in the smaller shower space, leaving you just the other two showers for the combi to cope with, what are the chances of both showers needing to be used at the same time - slim to none I would say. Washing machines/dish washer are cold fill these days, so not something to be considered for the combi. I don't agree with a comment I saw about electric showers being poor, modern high power ones are perfectly acceptable, we use ours daily - they are much better than the original 7Kw jobs were two decades ago.
     
Loading...

Share This Page