Conventional boiler.... comeback Combi all is forgiven!

[Dan Robinson]

From the horses mouth:

The Q51c has to have a low loss header the pump in the boiler is a modulating pump which is looking the correct flow through the boiler once the system gets hot the boiler will cycle on off. The house will never stay hot.

The DHW demand for a bath will be at least 9/12 L/min so 2 baths will require 18/24 L/min.
The Q51c will provide up to 23.2 L/min at 38d down to 13 L/min at 60d.
Is the incoming mains water pressure up to the required flow rate anyway ?

I agree with you that a system boiler with a cylinder is best design option although wouldn't like to comment on the customers state of mental health.

Or is TMW going to be ignorant enough to say the manufacturer doesn't know their own products?

 

[Tom1981]

It's naive to put your blinkers on for just one brand, there's lots of kit out there which is sold as the best thing since sliced bread.

An intelligent man will assess properly, cost up as use the cheapest and easiest route meeting the customers needs.

I'm rather good at fixing these awesome boilers, wouldn't it be great if they could make a appliance that just worked, but then that wouldn't be much fun would it? And I'd be out of a job

Hence why the likes of you give customers a poor deal.

How do I give someone a poor deal? Been able to order the parts for next day in most scenarios, same evening/nightime emergency call outs which I do alot of, and a healthy van stock means I'm quiet a welcoming sight to customers. Of course there are times things can't be fixed, but thats when their really old beasts.

It doesn't cost my (our) customers anything extra for me (us) to fix their appliance. A slight rise in their premiums if the parts are expensive or frequent call outs. On this note, ATAG parts are mostly Special Order items from the makers, and the ones that are available straight away are pretty expensive. I had a quick search in our parts screen and was surprised to find only a handful of appliances listed with parts. Appears these ATAGs aren't as popular as made out by yourself and I sure would be pushed to fix one in a short space of time.

 

[Nige F]

We dont actually know how big his cylinder is.


Tony

View media item 61650
looks like a 42" (140ltr) not exactly big enough for a 3 bathroom property.

Did you work that out from the length of the door handle on the left

 

[Nige F]

Would having it one "once" use a lot more energy?

Is this the Last Post by jdillon the Original Poster

 

[picasso]

Did you work that out from the length of the door handle on the left

Whats your guesstimate then ?

 

[SimonH2]

This is what the MOD wrote below. Then BANNED me. I have not given any abuse or insults. Insults were directed to me by rip-off plumbers ON A DIY forum!!!! These rip-off plumbers should not be here.

So you've been unbanned, and come straight back with more insults. If you can't see that the words I;ve quoted above are an insult to honest tradesmen then you really do have a cognitive problem.

In the real world, such a combi doesn't exist - so we have to make compromises.

They are nearly there though. The lowest output of a large ATAG is approx. 8 kilowatt, which is meant for a large house and would not cycle much as the lowest heat demand for such a house would not be 0.5killowat. By the time such cycling starts the house temp sensors would kick in a cut out the burner. You could have a boiler that goes from 0.9 kw to 10kw and then add a 40kw boiler with both staged and both feeding a plate heat exchanger fro DHW, if you want to go right down to near zero output.

The point is a large output quality combi vs. a system boiler/external controls/unvented cylinder. The combi wins hands down.

Don't know if I should laugh out loud until my sides ache, or cry that someone could be so out of touch.
So having criticised an "S Plan" system as being horrendously complicated, you now propose two boilers, interlocks, complex plumbing, and external PHE And your assumptions are wrong anyway, seriously you show that you don't understand the real world.

For a real example. In the flat, a 30kW combi was inadequate - bath filling was slow, and when the flow restrictor was set wrongly I'd have to explain to the tenant how to turn the hot tap down a bit to get the water hotter. 40 or 50kW would have been better.
Now, you reckon heating load won't be less than 500W for any property where a large combi is justified ? OK, the heating load for the flat was 2kW measured in the cold spell at the end of 2010. I know that because I was testing the thermal store setup and ran it on electric for a while so I could easily measure heat input - it used 2kW to keep the flat at a comfortable temperature. To suggest that the minimum heating load won't be less than 1/4 of the max is not very credible.
OK, it might not be the natural installation for a big ATAG, but it's real world figures, from a real world property.

And I'd prefer that the heating ranged down rather than cycled on and off. Cycling on and off creates temperature and air movement variations which contribute to a feeling of discomfort. I seriously doubt if there are many system which cycle on a room stat where the rooms don't alternate between cold rads with a downdraught from the windows, and warm rads with a compensating updraught. In such a situation, occupiers will tend to turn the stats up a bit so as not to feel cold feet during the latter stages of the off periods. All the literature I've read suggests that UFH allows rooms to be kept at lower temperature precisely because it eliminates the cold feet syndrome.

 

[TellMeWhyyy]

This is what the MOD wrote below. Then BANNED me. I have not given any abuse or insults. Insults were directed to me by rip-off plumbers ON A DIY forum!!!! These rip-off plumbers should not be here.

So you've been unbanned, and come straight back with more insults. If you can't see that the words I;ve quoted above are an insult to honest tradesmen then you really do have a cognitive problem.

In the real world, such a combi doesn't exist - so we have to make compromises.

They are nearly there though. The lowest output of a large ATAG is approx. 8 kilowatt, which is meant for a large house and would not cycle much as the lowest heat demand for such a house would not be 0.5killowat. By the time such cycling starts the house temp sensors would kick in a cut out the burner. You could have a boiler that goes from 0.9 kw to 10kw and then add a 40kw boiler with both staged and both feeding a plate heat exchanger fro DHW, if you want to go right down to near zero output.

The point is a large output quality combi vs. a system boiler/external controls/unvented cylinder. The combi wins hands down.

Don't know if I should laugh out loud until my sides ache, or cry that someone could be so out of touch.
So having criticised an "S Plan" system as being horrendously complicated, you now propose two boilers, interlocks, complex plumbing, and external PHE And your assumptions are wrong anyway, seriously you show that you don't understand the real world.

For a real example. In the flat, a 30kW combi was inadequate - bath filling was slow, and when the flow restrictor was set wrongly I'd have to explain to the tenant how to turn the hot tap down a bit to get the water hotter. 40 or 50kW would have been better.
Now, you reckon heating load won't be less than 500W for any property where a large combi is justified ? OK, the heating load for the flat was 2kW measured in the cold spell at the end of 2010. I know that because I was testing the thermal store setup and ran it on electric for a while so I could easily measure heat input - it used 2kW to keep the flat at a comfortable temperature. To suggest that the minimum heating load won't be less than 1/4 of the max is not very credible.
OK, it might not be the natural installation for a big ATAG, but it's real world figures, from a real world property.

And I'd prefer that the heating ranged down rather than cycled on and off. Cycling on and off creates temperature and air movement variations which contribute to a feeling of discomfort. I seriously doubt if there are many system which cycle on a room stat where the rooms don't alternate between cold rads with a downdraught from the windows, and warm rads with a compensating updraught. In such a situation, occupiers will tend to turn the stats up a bit so as not to feel cold feet during the latter stages of the off periods. All the literature I've read suggests that UFH allows rooms to be kept at lower temperature precisely because it eliminates the cold feet syndrome.

First there was NO insult by me. You have an odd idea of what an insult is. This is a DIY forum, and one poster continually tells DIYers to only go to pros. I would throw him off the forum. These guys need to go to closed plumbers forum where they can boast of how much money they made by selling unneeded equipment.

It is clear you are total amateur and an enthusiast for thermal storage. That is OK, do what your fancy takes you to. Thermal stores are the ideal solution in many cases - but not yours. I did a search and saw your large thermal store in a 2 bedroom flat. In the practical case of a larger quality combi, instead of the unneeded bulky kit you have there, would have been the ideal solution, not taking up most of a small garage with a large cylinder.

Again, the prime point is a large quality combi vs. a quality system boiler/quality controls/large quality unvented cylinder. The combi wins hands down. Look at the figures and average demands of a domestic house.

 

[Dan Robinson]

So even when the manufacturer thinks you're barking. AND your figures have been discredited by EVERYONE else; professional and diy alike. ...you maintain your way is the best?



NURSE!

 

[TellMeWhyyy]

So even when the manufacturer thinks you're barking.

You are the one who wants to fit needed expensive cylinders all over. If the man has a body jet shower (very popular these days) the combis is the ONLY solution. The combi can deliver about 500 litres in 20 mins. 750 litres in 30 mins. How much to buy is that quality stainless 700 litre unvented cylinder? Plus the cost of reinforcing the floor.

Again, the prime point is a large quality combi vs. a quality system boiler/quality controls/large quality unvented cylinder. The combi wins hands down. Look at the figures and average demands of a domestic house.

 

[Dan Robinson]

I don't have a combination boiler. But I do have 2 showers with body jets. Come on. Even Atag have said an unvented cylinder is better. As well as having to have a header. Which also requires another pump.

So we have to pumps and a diverter valve and a calorifier and a huge gas pipe and probably a meter upgrade and a boiler over 2 feet wide.


SERIOUSLY. ...

 

[Corgigrouch]

Remind us again, Your experience of a large quality combination boiler is an ATAG A350EC isn't it?

 

[Dan Robinson]

So you have no practical experience outside of your own mid range boiler and spme googleering.

 

[TelllMeWhy]

I don't have a combination boiler. But I do have 2 showers with body jets. Come on. Even Atag have said an unvented cylinder is better. As well as having to have a header. Which also requires another pump.

So we have to pumps and a diverter valve and a calorifier and a huge gas pipe and probably a meter upgrade and a boiler over 2 feet wide.

SERIOUSLY. ...

The point is the DHW not whether a header is needed or not. And my experience of makers is that most do not know much about their own products and go for only one solution which they know works without looking at other solutions.

Many years ago before big combis. A friend had just bought a big 2 bath house and was broke in the process. The cylinder was a direct 300 litres and heated by electric immersions. The place was heated by solid fuel and gas fires. He could get a FuelSaver with a copper heat exchanger for next to nothing and he had a brass pump. As it was soft water, I suggested hooking the FuelSaver boiler directly to the cylinder, as all was non-ferrous. It worked brilliantly. It sent hot water directly to the top of the cylinder, giving usable hot water in minutes. But the makers disapproved because only "primary" water should run through the boiler. When he could afford to put rads in he put in separate boiler for the rads. The FuelSaver lasted 15 years until the copper cylinder leaked then he bought a smaller SS cylinder and hooked it up to the rads boiler. But the makers disapproved because only "primary" water should run through the boiler. Which was total balls in a soft water area.

A boiler 2 foot wide is a lot smaller than a gigantic cylinder. A large ATAG can do a body jet and he can be in it all day and NEVER run out of hot water.

 

[Dan Robinson]

Its wider than your average airing cupboard. Of which i have seen far more than you.

It is not significantly less complicated. It DOES need a header for the HEATING to work otherwise what is the point of a COMBINATION boiler?

Unless you can think of any other boilers that are half decent and can do 25 litres of more than tepid water per minute.

AND as stated repeatedly. Having such a stupidly oversized boiler for heating will cause short cycling, unreliability and poor efficiency.

You my friend know nothing. And, judging by the number of times you get banned from here have very little in life to keep you occupied so you have to come online under various guises to get your jollies.

And for that you have my deepest sympathies.

It's a shame as it wastes everyone's time and only serves to demonstrate how you're obviously not wanted around here.

 

[TelllMeWhyy]

A header can be a couple of tees, nothing special. You are a hands on plumber not a design man. Design & Spec is out of your range. Take note of the educated and experience people.

An airing cupboard to take a needless 400 litre cylinder is a lot wide than 2 foot !!!!!!!!!!!!!