I have thought about it. What is the reason that you think I have missed?
Can I have a new combi boiler and keep my hot water cylinder
- Thread starter blondebier
- Start date
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M
mysteryman
Doitall's last was correct, you can use a thermal store for DHW only, and supply the rads from the boiler with weather comp.
Weather compensation varies the flow temperature to the radiators inversely with outside temperature. If you put a Y Plan on the central heating side of a combi, the flow temperature has to be set permanently high so as to heat the connected cylinder. Therefore you can't weather comp it.
Keep it simple - there is less to go wrong.
Weather compensation varies the flow temperature to the radiators inversely with outside temperature. If you put a Y Plan on the central heating side of a combi, the flow temperature has to be set permanently high so as to heat the connected cylinder. Therefore you can't weather comp it.
Keep it simple - there is less to go wrong.
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FAO mysteryman, For someone that didint want to complicate things, I am not sure why you brought weather comp into the equasion? there are boilers on the market that will take two inputs, one with w/c and the other for the hot water, the op has 16lpm incoming on the mains, would you still recommend an unvented cylinder ?
COME ON GUYS, KEEP YOUR ANSWERS PROFFESSIONAL,PLEASE
are you now the new moderator ?
why not try reading the thread before repeating what already has been said.
COME ON GUYS, KEEP YOUR ANSWERS PROFFESSIONAL,PLEASE
are you now the new moderator ?
why not try reading the thread before repeating what already has been said.
fair enough, im gonna go and do a couple of jobs. see what weird and wonderful things have been suggested when i come backIts either this or talk to the wife
Yup, silly money for thermal store - not even a pressure vessel. Build up the lagging around the cold tank and run just shower direct from combi (9 litre/min from 27kW is better than 60A electric shower or non-pumped shower from vented cylinder). As you say, pumped shower from vented tank if you don't mind expense, noise, water meter and shortish showers. Some members of my family can stay under the shower for 40 minutes, but then I have an upgraded water feed, 2x25kW system boilers and a 300 litre unvented cylinder restricted to 13 litre/min by the shower head.this is all quite funny. I will put good money down that the op will get some people into quote and will end up with a replacement heat only boiler and a shower pump
still it keeps you lot busy.
this is all quite funny. I will put good money down that the op will get some people into quote and will end up with a replacement heat only boiler and a shower pump
No, I've got that at the moment and I want to replace it.
I'm going to get someone in and tell them what I want. Not the other way round. (I've heard of countless people getting screwed for stuff they didn't want or need.)
Thanks to all who have posted constructive suggestions. I like the thermal store idea.
I'm not overly concerned about the cost. As long as the system is efficient and works well I don't mind paying a bit extra for it.
In a ideal world, if I knew a combi would never break down I would go for one without hesitation. The boiler we had in our last house was great!
We now have a baby and ever being without hot water is not an option. The thermal store seems to be the ideal backup solution for our needs.
Cheers,
Blondebier
The simple answer is that you cannot use a combi boiler fitted with weather compensation to heat rads and a HW cylinder. This is because the weather compensation will then control the flow to the heat coil of the cylinder. Depending on the outside temperature, that may result in some inappropriate boiler flow temperatures.
The more involved answer is that it IS possible to connect a combi boiler in a Y plan but with hot water priority. But that will need a relay to insert a potentiometer in place of the weather sensor to be adjusted to give a flow temperature of about 70°. If the flow rate is correct, this will enable the cylinder to reheat whilst the boiler is still working efficiently.
But doing that needs some more advanced knowledge of boilers and heating systems and the ability to design and set up non standard equipment. It will also mean that a Yellow Pages plumber you call later will not understand it.
Tony
PS This was previously posted on another thread in error but it does still fit there and as I only had phone access I was unable to correct it at the time.
The more involved answer is that it IS possible to connect a combi boiler in a Y plan but with hot water priority. But that will need a relay to insert a potentiometer in place of the weather sensor to be adjusted to give a flow temperature of about 70°. If the flow rate is correct, this will enable the cylinder to reheat whilst the boiler is still working efficiently.
But doing that needs some more advanced knowledge of boilers and heating systems and the ability to design and set up non standard equipment. It will also mean that a Yellow Pages plumber you call later will not understand it.
Tony
PS This was previously posted on another thread in error but it does still fit there and as I only had phone access I was unable to correct it at the time.
M
mysteryman
Tony is almost 100% correct.
It can be done with a Vitodens 200-W combi, but anyone else coming to work on it would be scratching his head.
I believe that the OP is planning far too complex a job. Look to your mains flow rates first!
It can be done with a Vitodens 200-W combi, but anyone else coming to work on it would be scratching his head.
I believe that the OP is planning far too complex a job. Look to your mains flow rates first!
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