Upgrade to system - Unvented or combi
I was looking for some advice on this probably popular subject. Iam doing my bathroom so with to upgrade my shower from the old Mira power shower to a 'normal' mixer shower. I have a gravity vented hot water system (160l) just now so require a method of boosting the pressure for the shower. I had originally thought of a shower pump or digital mixer system that would boost the pressure but understand these can be noisy. I also have another en suite (not presently used but will be in due course) there are 2 adults and 3 children so its conceivable that more than 1 person will require a shower at the same time in the future. I then started to think about the other options of unvented or combi as i have also thought of replacing the boiler soon as its 20 year old and obviously not very efficient.
Along with others i guess i have then received different advice/opinions of which would be best for me and the claims for each made:
High flow combi (Worcester 440, Valiant 937 store, Baxi duotec 42KW (or heat saver but very exspensive) - cheaper to install, claimed cheaper for hot water as only on demand.
Unvented - More efficient for potential high usage as when heating on only like an extra radiator and system boiler will run at a lot lower rate than a combi, better for multiple usage.
Did a crude measurement of the tap in my garage that tees straigh off the main as it enters the house, gettimg about 24 l/min but from what looks like a 12mm pipe for this section does this matter? Also measured off the kitchen tap at 10 l/min but have heard they are normal low anyway. The guy championing the unvented says the stated flows for the combis are based on a 35 degree rise in temperature so when the inlet temp drops in the colder months the boiler cannot produce the same flow rate as stated. Measured just now as its snowing and its 8 degc and guess it could easily drop to 5 degc so hot water of 40 - 43 degc would not be hot enough i guess. Awaiting one guy to come back and properly measure the flow & pressure.
What would be the acceptable limits for these for either system?
While looking at boilers have seen the Baxi gas saver not cheap at £700 but cheaper than solar thermal and claims to reduce hot water heating requirements, anyone used one?
Forgive the long winded text that is probably a bit of waffle but very confusing when speaking or reading all the different views. The high flow combis look good in theory but do they work as well as claimed and anyone used the VAliant 937?
Or do I take the easy option and fit a shower pump?!!
I was looking for some advice on this probably popular subject. Iam doing my bathroom so with to upgrade my shower from the old Mira power shower to a 'normal' mixer shower. I have a gravity vented hot water system (160l) just now so require a method of boosting the pressure for the shower. I had originally thought of a shower pump or digital mixer system that would boost the pressure but understand these can be noisy. I also have another en suite (not presently used but will be in due course) there are 2 adults and 3 children so its conceivable that more than 1 person will require a shower at the same time in the future. I then started to think about the other options of unvented or combi as i have also thought of replacing the boiler soon as its 20 year old and obviously not very efficient.
Along with others i guess i have then received different advice/opinions of which would be best for me and the claims for each made:
High flow combi (Worcester 440, Valiant 937 store, Baxi duotec 42KW (or heat saver but very exspensive) - cheaper to install, claimed cheaper for hot water as only on demand.
Unvented - More efficient for potential high usage as when heating on only like an extra radiator and system boiler will run at a lot lower rate than a combi, better for multiple usage.
Did a crude measurement of the tap in my garage that tees straigh off the main as it enters the house, gettimg about 24 l/min but from what looks like a 12mm pipe for this section does this matter? Also measured off the kitchen tap at 10 l/min but have heard they are normal low anyway. The guy championing the unvented says the stated flows for the combis are based on a 35 degree rise in temperature so when the inlet temp drops in the colder months the boiler cannot produce the same flow rate as stated. Measured just now as its snowing and its 8 degc and guess it could easily drop to 5 degc so hot water of 40 - 43 degc would not be hot enough i guess. Awaiting one guy to come back and properly measure the flow & pressure.
What would be the acceptable limits for these for either system?
While looking at boilers have seen the Baxi gas saver not cheap at £700 but cheaper than solar thermal and claims to reduce hot water heating requirements, anyone used one?
Forgive the long winded text that is probably a bit of waffle but very confusing when speaking or reading all the different views. The high flow combis look good in theory but do they work as well as claimed and anyone used the VAliant 937?
Or do I take the easy option and fit a shower pump?!!
