Combi + Hot Water Tank - how to sort out my hot water system!

[shrub100]

Hi All,

I have just purchased a house and as part of my renovations want to sort out the hot and cold water system. The previous owners clearly had to make some tactical and maybe short-sighted decisions as one of the occupants could not use the stairs and therefore needed a downstairs shower room. As a result I am left with a rather strange situation which I am hoping to get your advice on prior to a visit by my plumber on Wednesday.

Current situation:

• 4 bedroom house (spread over 3 floors)
  • 1 upstairs master bathroom with shower and bath
  • 1 downstairs bathroom with shower
  • Standard kitchen
  • Currently only 2 occupants
• Worcester 25si Combi Boiler (3yrs old)
  • Runs central heating throughout house
  • Currently runs hot water in only the downstairs shower room (direct feed from mains)
  • Seems like it could be underpowered for the size of house?
• Standard vented hot water tank with 2 electric immersion heaters
  • Runs hot water in upstairs bathroom (shower has a horrid wall mounted pump)
  • Runs water in kitchen
  • Standard Plastic Cold Water Tank
• Water tank needs replacing as it is bulging and has a small crack
  • Feeds upstairs bathroom, kitchen and hot water tank
• Water pressure
  • Thames Water (house situated very near the pumping station)
  • Good pressure at all times of day (previous plumber indicated pressure was not an issue when he tested it)
  • 15mm mains inlet so volume may be an issue
  • The whole estate is mainly elderly people who have the old water tank / hot water tank system. I would imagine pressure might start becoming an issue over the next 10 years as new couples move in.

As you can see this is a slightly weird set-up. In terms of my requirements for the hot water this is them in a priority order (1 = most important):

1. Power
   1. I will be keeping both bathrooms with Shower in both rooms. I will be unlikely to use both showers simultaniously for 5-7 yrs if/when we have children.
   2. I am planning on rainfall type shower heads in both shower rooms and understand that it is best to have good pressure and volume for these to be effective.
2. Noise
   1. I am keen not to have the whole house woken up when anyone has a shower. Pumps have probably gotten better since I had one installed 10 yrs ago, but imagine that they still generate a decent amount of dB!
3. Efficiency
   1. I would prefer not to heat a tank of water and have a combi boiler running. It seems inefficient to heat hot water in a tank only to then heat different water when taking a shower.
4. Longevity
   1. I am rennovating the house at the moment and want to ensure that any new pipe work/ wall chasing etc is completed now so that I do not need to redo this work in the future. Whilst my requirements on hot water are not great at the moment, I plan to be in this house for 10+ years when my family will likely be larger and hot water requirements will increase.
   2. I would not mind replacing the combi boiler with a larger unit in 5-7 years if water requirements increase. Equally if replacing it now makes the most sense then this is also an option
5. Cost
   1. Cost is a consideration, but doing the right thing for the future is more important to me.

What would you all suggest I do to the house? To be honest I am confused by the options as none of them seem ideal. It almost feels like I should either keep a cold water tank and hot water tank and suppliment them with a pump (in which case I likely need a new non-combi boiler to heat them all). Or that I need to dig my drive up, install a larger mains inlet and then in the future upgrade the Combi to a larger capacity one when the family grows in size.

Please let me know your ideas. No option is too stupid. One plumber even suggested pumping water from a new cold water tank through my Combi? An innovative and novel idea or completely stupid?

Thanks in advance for your suggestions.

Jon

 

[Mike Jackson]

I would keep the combi and run the kitchen hot from it. If flow is available fit an unvented cylinder to run the two bathrooms and use the combi like a system boiler.

 

[mfgs]

I would keep the combi and run the kitchen hot from it. If flow is available fit an unvented cylinder to run the two bathrooms and use the combi like a system boiler.

What he said is the best option.

 

[stevetheplumber]

i always think its best to put one shower on the combi you can always get hot water from a shower in an emergency or when the cylinder isnt fully heated but cant shower in the kitchen sink

 

[Centralheatking]

Or stick a lecky one in somewhere CHK

i always think its best to put one shower on the combi you can always get hot water from a shower in an emergency or when the cylinder isnt fully heated but cant shower in the kitchen sink

 

[shrub100]

Thanks for all the suggestions. Just had my plumber round and he had fairly similar suggestions:

• Keep the downstairs shower off the Combi
• Remove the cold water tank
• Unvented cylinder in the attic - 180l
• Replace combi in 5-7yrs time with a larger one to meet the demands of a growing family

What to you all think?

This is all good and well, but he noted that whilst mains pressure was good, the volume through the 15mm connection was rubbish and is currently giving me 12 ltrs/min. He therefore suggests getting a 25mm pipe installed from the mains to ensure that the property has enough water volume coming through the house.

The question I have for everyone then is roughly what will Thames Water charge me to upgrade the mains piping? I know this is a question with infinite answers but on the basis of:

• Replace existing 15mm with 25mm Poly
• Water meter will need replacing
• It looks like the mains is in the pavement rather than the road

Also will Thames water bring the water into my house with the mains stopcock, or does my plumber need to run the pipe from the new meter to the house? The outside meter is only a car length to the house. so the excavation should not be that bad.

I did ask my plumber, but he admits he doesn't have much experience with getting new connections to the mains!

Thanks again for your advice,

Jon

 

[shrub100]

Following on from this, is it possible to bore a hole into the house without having to dig up my front door step. I have no issue with digging up my garden and even cutting a big hole in my driveway paving outside my house, but my front entrance is tiled so it would be good to go the last 1.5 meters from underground. I have heard of using a mole, but wonder if there is a more cost effective method for a very short distance? Any idea / experience.

 

[stevetheplumber]

if you have a meter you can run the new poly to that, most meters are feed by poly on the board side if the meter is close to the boundary you can do it by under cutting the pavement as your not supposed to mess with the councils pavement
a mole will only go through soil basicly so you will need a hole into the house, can it go in to the void below the floor some where other than under the tiled floor?then pull the poly in to a postion to conect to existing
weve done it by using drain rods to get a rope through to the middle of a terraced house then pulling the poly throughtwo handed job one inside pulling and one out side feeding it in