Boiler recommendation fro 5 bedroom house

[Milleniumaire]

We bought a new 4 bedroom house 8 years ago fitted with a Saunier Duval Thelia Twin 28E combi boiler which provides both heating and hot water. A couple of years ago we converted our loft into a room with en-suite bathroom so we now have:

5 rooms downstairs - utility, kitchen + sun room, lounge, office, toilet, hallway - 6 radiators 5 rooms on 1st floor: 4 bedrooms, 1 en-suite bathroom, house bathroom - 7 radiators 2 rooms on 2nd floor: bedroom, bathroom - 3 radiators

In total there are 16 radiators of various sizes, 3 showers, 2 baths and 6 sinks. There is a 7 day programmable thermostat in the hallway and all radiators are fitted with TVR's. The current boiler is large and resides in the garage.

My wife and I and our three young boys (12, 10 and 6) live in the property. Usually, we only tend to use one shower at a time, partly because even running a tap will reduce the shower water pressure, however, as our eldest has started showering every day there is more chance that two showers will be going at the same time in the near distant future so we would like a boiler that could manage this. We would also prefer a boiler with a small hot water storage cylinder so that hot water is always instantly available. I believe the Thelia Twin has this.

We have a **lot** of problems with our current Saunier Duval boiler and it didn't take me long after moving in to realise that the builder had cut his costs by installing this make of boiler. I suspect that the current boiler problems are due to the increased heating requirements caused by the loft conversion (although the developers told us it would be fine), its age and the fact that I believe it is a poor quality boiler. We currently pay insurance for a 3* boiler maintenance contract and to have the boiler serviced annualy.

I would appreciate any recommendations on what boiler we should use if we were to replace our Thelia Twin. Obviously, I would prefer a boiler that is efficient and reliable and that could handle the extra heating load, be capable of feeding two showers simultaneously and storing hot water.

Thanks.

[David Hansen]

On 7 Nov 2006 05:51:40 -0800 someone who may be "Milleniumaire" wrote this:-

Despite what some may claim, instant water heaters, of the sort one sees in houses, won't run all of this lot. What you need is a stored hot water system, probably with a fairly large amount of storage.

The number of cylinders, their location and their size depends on the precise layout of all the outlets and the house. An instant heating setup may be suitable for feeding a few sinks near the boiler, in which case one cylinder elsewhere may be sufficient.

Consider a thermal store as well.

[PeterK]

Have a look at

Its an expensive (over £3k) floor standing combi boiler that may address your needs without major plumbing work. It has a significant inbuilt hot water store so can deliver

400l with a 40deg rise for the first 10 mins. I was very impressed with their regional sales rep - he'll call round after commissioning to check the installers work! - a spin off from them being commercial boiler manufacturers? In the end with no space constraints I've gone down the heat bank route - With the disruption and commercial plumbing charges I doubt there is much "cost" difference. There was some very constructive discussion about the boiler on the group in 2005 at starting around post #68 of 293!

PeterK

[Ed Sirett]

Read the Boiler Choice FAQ as a starting point. Get some idea of the space heating requirements by measuring up and doing the sums (see FAQ). The HW system should be based on the number of people that could plausibly, regularly inhabit the house (not the worst case), allow 25 litres per person.

[Doctor Drivel]

Don't. It is 20 years out of date.

[Doctor Drivel]

If all outlets were on, a stored water system would trickle out too.

Sensible.

[Doctor Drivel]

A Rinnai multi-point will do the same flow rates as a stored water system. You have to be realistic, what he needs is a system that can cope with 3 showers at 7 litre/minute. Two baths on together is so rare.

[Doctor Drivel]

Was that 3K fitted? I have seen them for sale at £2,300 just for the unit. But £3K for a 2.3 to 3 bathroom job is quite cheap. Compare that to a boiler and large unvented cylinder and the ACV wins, and takes up less space and is all stainless steel.

The ACV is a class act. An unvented cylinder/thermal store hybrid, that also condenses even in summer on just DHW.

One alternative for the poster is have a Rinnai or Andrews multi-point two bathroom water heater. They have models that can go outside on the wall. This will deliver the DHW flows no problem. The Rinnai is the largest selling water heater in the world - made in Japan and a class act. They have a remote waterproof temperature controller. You can be in the bath or shower and set the temperature. The Andrews is also made I think in Japan by Rinnai or a competitor.

Then if the old boiler is fine on just CH, disconnect the troublesome DHW section - it may need water inside, so just cap up the outlet pipe to the taps. Or if the boiler is shot, buy one sized to suit the CH demands.

A problem will be that if both are on at the same time the gas meter will be too small. The way around this is have a flow switch on the cold feed to the Rinnai. Run the CH boiler room stat circuit through this and the room stat. When the Rinnai demands hot water the CH is turned off. No cylinders, tanks and two girls can stay in the shower for ever more and not run out of hot water.

Look at Rinnai and Andrews:

[Dave Fawthrop]

|>>3 showers, 2 baths and 6 sinks. |>

|> Despite what some may claim, instant water heaters, of the sort one |> sees in houses, won't run all of this lot. What you need is a stored |> hot water system, probably with a fairly large amount of storage. | |If all outlets were on, a stored water system would trickle out too.

Depends on the size of the store, and the diameter of the pipes. 22 mm everywhere would be a good idea, An extra large tank and an extra large cylinder also.

|> Consider a thermal store as well. | |Sensible.

[Dave Fawthrop]

|>>3 showers, 2 baths and 6 sinks. |>

|> Despite what some may claim, instant water heaters, of the sort one |> sees in houses, won't run all of this lot. | |A Rinnai multi-point will do the same flow rates as a stored water system. |You have to be realistic, what he needs is a system that can cope with 3 |showers at 7 litre/minute. Two baths on together is so rare.

How many/few women do you have in your household ;-)

[Doctor Drivel]

You will need 28mm and above in a lot of it and the sizes of cylinder pipes, etc will be then commercial. You can get commercial instant DHW multi-points too. The aim is to be sensible about DHW demand.

[Doctor Drivel]

As I said...Two baths on together is so rare.

[Doctor Drivel]

Good thread. A shame the uk.d-i-y Lunatic Association (affiliated) ruined it.

[Dave Fawthrop]

|> |>>3 showers, 2 baths and 6 sinks. |> |>

|> |> Despite what some may claim, instant water heaters, of the sort one |> |> sees in houses, won't run all of this lot. |> | |> |A Rinnai multi-point will do the same flow rates as a stored water |> system. |> |You have to be realistic, what he needs is a system that can cope with 3 |> |showers at 7 litre/minute. Two baths on together is so rare. |>

|> How many/few women do you have in your household ;-) | |As I said...Two baths on together is so rare.

If I had two baths *they* would always want a bath at the same time :-(

OP has several boys, Hope they do not play in the same football team.

[Bob Eager]

Whereas Drivel is 100 miles out of touch with reality.

[Doctor Drivel]

I've seen what you write.

[Matt]

Falls off chair in astonishment So the pills are working then?

[Doctor Drivel]

Lord Hall, no your pills are not working, you fell off the chair. You need to attend the clinic more.

[David Hansen]

On Tue, 7 Nov 2006 20:35:38 -0000 someone who may be "Doctor Drivel" wrote this:-

That depends on the number of cylinders, as well as the pipework and head. It would certainly be possible to design and build a system where the water trickled out of some of the taps if they were all turned on, but that's not something anyone other than a cowboy would do.

[Doctor Drivel]

You are missing the point. You can make a stored water system deliver the required full flow with all taps full on. It will be very big and in a domestic situation far too large for representative use.

You can do the same with an ionstant watyer heating system, there again far too large for representative use.

What you wrote was: "Despite what some may claim, instant water heaters, of the sort one sees in houses, won't run all of this lot".

Some actually will. However you are not familar with these sort of installations.