Help designing new boiler solution

[robbb]

Hi all,

After my crappy situation I’m in at the moment (New member, can someone help check quality of this boiler install?) we are going to get it all taken out and done properly as its not fit for purpose (Hot water tank too small, poor install etc etc)

I’d really appreciate some input here based on our requirements:

Heating / Hot Water

• Install system capable of running 2 Mira Mode Digital showers concurrently for approx 10-15 minutes of simultaneous use.
• Relocate existing HW tank to loft and make good previous botched install by non gas safe trader. May need to replace 18KW Worcester Greenstar based on below.
• If mains water pressure is adequate explore the option of installing unvented cylinder (Megaflow, approx 250l-300l) to supply the 2 showers to the above spec OR vented cylinder with 250l-300l capacity.
• Make good airing cupboard to be used as storage and remove unnessesary tanks if moving to unvented.
• Optional considerations: Replace 8 x Radiators (4 bedrooms, 2 lounge, 1 dining room) with higher BTU rated based on room requirements with and install rads with TRV. Current bedroom rads are small single 450x600mm with low output.
• Supply and install adequately rated boiler based on requirements (Worcester Bosch 24KW/30KW or relevant spec based on home requirements).
• Fit of boiler / tank and piping to a neat and tidy standard.

Above are our requirements, does this seem sound?

Gas supply is 15mm form meter to airing cupboard.
Water supply is likely 15mm to loft.

After the last install we want to do it all ‘properly’ and realise its going to be a lifetime investment! Lesson learned, buy cheap buy twice!

 

[ShaunCorbs]

are the two digi showers pumped ? as if this is the case you either need to keep with your set up eg tank and cylinder or change the units

 

[robbb]

are the two digi showers pumped ? as if this is the case you either need to keep with your set up eg tank and cylinder or change the units

Yes pumped, but I don’t mind changing the mixer to high pressure (I know this is extra cost). I couldn’t see many high capacity (250l+) hot water cylinders hence unvented option, and from my research (feel like I’m getting an understanding now, from absolutely zero 2 weeks ago!) the unvented is a pretty pukka job, providing supply is adequate.

 

[ShaunCorbs]

first thing you can do to help is, is to measure the incoming water supply flow and pressure

 

[Chuck]

I recommend that you don't waste time trying to design the system yourself. Instead, spend it finding a couple of local heating engineers who have a good reputation. (Family firms that have been in business for a couple of decades or more are often a good bet.) Discuss your requirements and priorities with them when they view the site prior to quoting.

 

[robbb]

I recommend that you don't waste time trying to design the system yourself. Instead, spend it finding a couple of local heating engineers who have a good reputation. (Family firms that have been in business for a couple of decades or more are often a good bet.) Discuss your requirements and priorities with them when they view the site prior to quoting.

I’m not wasting time designing it myself, simply trying to educate myself in a complicated industry so I can talk to some hearing engineers with some level of knowledge.

 

[SavageW]

Maybe ask on the find a plumber section of the forum,couple guys could be local to you? I understand that you want more knowledge on the design as you was let down by your previous bloke.When you get a new Guy to quote explain your situation an ask for things to broken down as you just want to make sure it’s goibg to suit your needs

 

[oz-plumber]

Why don't you keep the boiler for the heating and get a Rinnai tankless hot water unit.

It will need a larger gas supply from meter.

The units only use gas when unit is required for hot water.

The Rinnai water heaters ( or other brands ) would be about 70% of the market over here

 

[gmartine]

I think almost every member here would recommend an unvented cylinder for your situation if possible and as it sounds like you now know what you want take your spec and get two or three quotes from reputable installers. We'd be happy to chew over the details with you but if an engineer says yes to an unvented cylinder without measuring your incoming flow/pressure send them packing.

 

[king of pipes]

We will all hae a difference of opion on here robb, you have been let down badly by your rogue installer my advice is get some proffesional advise dont rush into anything , a 25mm mdpe main and 20+ litres a minute will be needed for a Megaflow , another option would be a valliant 937 i have fitted these on a 20mm supply with a good pressure and it worked fine you would have a dry loft no tanks no storage , no cylinder . no worries worth considering and discussing with the new installer. Cheers kop