Combi boiler and cast iron radiators

[ethans]

I've called two more plumbers to have a look, one being British Gas (to get their view as well). The first plumber came recommended from three friends that have used him, so I presumed he would be good.

My only brief to them was that I wanted something that would maintain current water pressure (or improve it) and be efficient, not sure if that led him to his recommendation?

Thanks everyone for all your help, I really appreciate it - this site is fantastic.

 

[Balenza]

gas4you wrote

A combi is more efficient

From reading this site I would say thats debatable !.
Their main benefit is that they are compact .


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If you cant fix it then leave it so no one else will !.

 

[JohnD]

The use of the word "Pressure" probably led him to a system run off the mains.

But you have a tall house, so a tank in the loft will give you a lot of pressure in the lower floors.

You can get greater flow from a tank and cylinder; with big pepes and taps, they can deliver water faster than the main can fill it.

But if you want the force of American-style showers on the upper floors, I think you would need a shower pump.

 

[Balenza]

ethans wrote

in a 4/5 storey house

We have only one master bathroom (with bath / shower / toilet / sink on the first floor)

I would fit one of Ranges open vented stainless cylinders. The head pressure should OK in this building.
Very professional looking. They spec the Sl 150 for 1 bathroom or shower based on guidelines given in BS 6700.
Reheat in 17 minutes with an 18.9kw coil in coil HEx.
Immersions are fitted so you have back up if the boiler fails.
If your mains water supply fails you also have back up.
You could opt for their twin coil version so solar or solid fuel is possible and giving more back up in the event of an electricity failure.
An unvented cylinder is a non starter here. Too much trouble and hassle with the discharge pipe.

 

[Balenza]

ethan wrote

(and did say he would need to replace the pipe from street to house to increase mains pipe size),

Just to add.
Mains pipe upgrading and UV cylinders . ££££££ Very expensive.
But the choice is yours .



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If you cant fix it then leave it so no one else will.!

 

[scatmanjohn]

I have cast iron rads throughout on a pressurised system, works a treat.

 

[John_D]

so many options each with advantages and contras

traditional open vent system new cold water storage cistern and high efficiency hot water with sealed boiler - gravity hot water pressure may not be acceptable

combi no cisterns or cylinders DHW flow rates may not be acceptable

unvented DHW need good supply of cold water as the pipe supplies all water for domestic use. will give powerful showers, must be installed by registered plumber and notified to local council building control, also needs
discharge pipe

to find the flow rate-fill a bucket from the kitchen tap and time how long it takes.
you also need good pressure for unvented or combi

there are also accumulators if the water pressure and flow are not as good as they were

it depends what sort of system you want

 

[gas4you]

gas4you wrote

A combi is more efficient

From reading this site I would say thats debatable !.
Their main benefit is that they are compact .


_____________________________

If you cant fix it then leave it so no one else will !.

Iwas just generally trying to point out the difference between only heating the water you use and heating a cylinder full of water that could cool before its use thus wasting it's energy used.

I also take on board Chris's point about gas used to heat the water over a lenght of time

 

[Paul Barker]

OP to keep the two sstems seperate wrap 8mm copper pipe which is quite flexible around the flow and return pipes from the radiators, then take them up to the roof to take advantage of solar power, pass all our cold water through these pipes before the go into a 24kw combi. ou should get a fantastic flow rate and our cast iron radiators will be unafected from the hot water.

 

[Balenza]

OP to keep the two sstems seperate wrap 8mm copper pipe which is quite flexible around the flow and return pipes from the radiators, then take them up to the roof to take advantage of solar power, pass all our cold water through these pipes before the go into a 24kw combi. ou should get a fantastic flow rate and our cast iron radiators will be unafected from the hot water.

A diy lash up for HW pre heating ??.
Sounds good if I knew what you was on about .
I think the OP will be confused enough at this stage without adding more complications !.

 

[Balenza]

gas4you wrote

A combi is more efficient

From reading this site I would say thats debatable !.
Their main benefit is that they are compact .


_____________________________

If you cant fix it then leave it so no one else will !.

Iwas just generally trying to point out the difference between only heating the water you use and heating a cylinder full of water that could cool before its use thus wasting it's energy used.

I also take on board Chris's point about gas used to heat the water over a lenght of time

You also need to take on board break down costs and employing engineers who are trained to a higher level to deal with the extra levels of control who will have higher charging rates !

 

[gas4you]

OP to keep the two sstems seperate wrap 8mm copper pipe which is quite flexible around the flow and return pipes from the radiators, then take them up to the roof to take advantage of solar power, pass all our cold water through these pipes before the go into a 24kw combi. ou should get a fantastic flow rate and our cast iron radiators will be unafected from the hot water.

Not all combis are suitable to have pre-warmed water in the cold inlet. They have to be solar rated.

 

[Dan Dan the Gas man]

ethans, do you mean that you don't want a system with a cold water tank in the loft, and a hot water cylinder?

I quite like this old-fashioned arrangement, and there are some very good system boilers around that will do it (you haven't got to convert to a combi or a Megaflow if you don't want to).

When the time comes that my cast-iron boiler expires, I have my eye on the stainless Vitodens. As the system boiler has fewer bits in it than the combi, it can be expected to go wrong less often.

I am just a homeowner.

TAKE YOUR EYE OFF THE VITODENS!!!

 

[JohnD]

TAKE YOUR EYE OFF !!!

here it is