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What boiler

Ive just moved into 5 bedroom house with 2x bathrooms which are 1x bath + shower and a separate shower room. There are four people in the house 2x adults and 2x young children under 5 . The details are I get 2.7 bar and 30l/m at the outside taps with no other taps running, I also get 17-18l/m from a kitchen tap. I'm looking to replace my current set up with either a large combi Worcester 440 or 550 or use a unvented indirect cylinder. The water connection to the boiler will be straight from the main input before it goes to the remaining tap What would be best for now and long term, my concern is that the 550 can give 25l/m but what happens after the internal water storage is spent ?My cylinder concern is what happens after the water runs out and reheat time , is the cylinder being topped up as it is being used and is it being heated at the same time as long as the HW time is on ?im looking to install 210lt or larger , the existing is only 140lt . Another issue is due to space I may put either the combi or the cylinder in the loft and then feed down the hot to loft shower room and the bathroom on the 1st floor and where possible rerun the pipes in 22mm , wil there be a big drop in bar or pressure by moving it to the cylinde though I guess gets back some due to the drop from loft o 1st for bathroom?I was even thinking of a two comi approach, one for main bathroom and another for the loft shower , remaining HW and CH needs? Obviously dearer Your thoughts would be welcomed Thanks
 
Unvented cylinder is the best solution. Think about the weight before siting the cylinder in the loft. 210l of water weighs 210kg, add that to the weight of the cylinder and you've got 1/4 tonne sitting up there.
 
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Mega flow unvented cylinder 210ltr or higher off mains pressure.
what 's your system now ? boiler and old cylinder?
 
twin coil unvented, so can be used for solar in future if need be, or selling point. Plus join the two coills together to get a quicker reheat time
 
Or fit a Worcester Bosch Highflow 550CDi , it'll offer a similar performance on your water main to the unvented and take up the spac
 
this is not a case of 550 cdi vs unvented its just a case of how expensive is it to install unvented ?how much space rerquired?

heat only boiler as well
 
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hi sorry I`ve not replied,

howsie is correct. I`m doing my house up and as I need to replace my vented system so to have a bigger space in the kitchen so I may as well change the boiler- small cost compared to the overall project cost I`m looking to save space in my kitchen and remove the pumps which the current showers use but still have the same flow. The idea is either a Worcester550 or a unvented -either a slim version so i keep it in the kitchen though I`m not sure if it will be big enough or a normal on but in the loft. The whole thing is as I`m doing the kitchen up then I need to help sure I "future proof it" .

I`m leaning towards a unvented but which on? I`m also thinking of having a dual coil version but connect both coils to the same boiler so have a quicker reheat time.

What boiler - do yo still size the system boiler on the number of rads, does the size of the cylinder need to take into account, reheat time etc ?

Just to add

the mains o/s tap is 30lt/m
2.7 bar
main is old lead though I`m looking to change it out ????- Does it matter though since if the cylinder is larger then I would use so as long as the cylinder does not run dry then it may taken longer to refill but the output is still 22mm? to the hot taps?
many thanks
 
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It's worth noting that the 550 weighs 130kgs (at least) and is the size of a washing machine. My parents have a 440cdi and the condensate pump (£200+) packed in after 3/4 years. The 440/550's are too expensive and have too many moving parts. I'd go for an unvented system, it will be better in every single way.


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I just saw lead and put the blinkers on. Haha. Looking at the figures it would be okay, but tbh probably still worth replacing if you're gonna have the house in bits.


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