Conflicting Opinions - a Low Loss Header or not?

[ironman1]

Doesn't sound like it would be an issue with a 4-pipe boiler with internal diverter valve using W-plan.

One of the primary reasons for low loss headers or 'loop' type headers is to avoid stratification across the heat exchanger/s (buffer) , without this header arrangement the heat exchanger can crack due to 'thermal shock' , this is normally the case when heating is being called for & boiler is already up to operating temp (HW)

To the OP...........i would consider going the header type route with you're installation , seems the guy would'nt quote for it if not necessary.

 

[Chris43]

I might agree with you for certain if I hadn't had two other quotes which didn't have a LLH as part of their solution. That makes me think it is either unnecessary or the other two quotes are offering me a solution that has a level of increased risk to the boiler. My frustration is that I can't quantify it.
And is £1500 + VAT a reasonable price for adding one at the same time as the whole boiler is being replaced? If it were £300, I don't think I would be quibbling, as that seems a not unreasonable price for an extra insurance policy. But £1800?? Thats the cost of a second boiler!

 

[Agile]

There are really three questions:-

x Is a LLH necessary?

x If not necessary then does it give an advantage?

x Is such a high installation price reasonable?

None of us have seen your installation so questions on cost are difficult to quantify.

Tony

 

[ironman1]

I understand you're frustration as you want a decent job done but don't want to pay for something you feel is unecessary ..................................problem here is heating & hot water is a 'given' in life & nobody wants to spend money on it , then again some would'nt be put out spending 5K on a holiday or an extra 2k on the price of a new car with all the bells & whistles , you state you have a 4 bedroom detaced house? , either go with one boiler with header arrangement or go with two seperate boilers , one for heating & one for hot water , going the two boiler route would possibly save some money as controls would be minimal.

 

[Agile]

What I can say is that 98% of four bed detached houses have NO low loss header and just ONE boiler!

Tony

 

[ironman1]

I guess technology moves on for good reasons.

 

[Chris43]

Thanks both.

Tony, you are right in that those are my questions,and I know that to ask a price, sight unseen, is a big ask.

Basically, the boiler is in a separate boiler house, plenty of space, and current pipework will have to be changed anyway, that is in the quote.

To instal a LL Header appears (!) to be a matter of connecting the LL Header to the boiler with the pump in the return circuit of this. Then the exisiting pipework would connect to the LLH rather than to the boiler. That makes few more connection, but all but the final ones are in new pipework. The final connection is what would have to be done withut an LLH and is included in the quote.

So ballparks? or a sensible range? I'm not trying to nickel and dime a negotiation, I'm happy to pay a fair price, whatever that is.

Thanks again for your help and attention.

 

[mysteryman]

I still don't think you need a low loss header. Spend the money on system cleaning, fit weather compensation, and in addition to all its other many benefits, you won't get thermal shock either.

Why not fit the boiler in the house? The sort of output you require can be provided by a neat and quiet boiler.

Don't over-specify!

 

[Chris43]

May I ask your reason for why I don't need a LLH. I'm not arguing, just to know helps me understand.

Why not in the house? well, we have a boiler house, which would mean a major kitchen rebuild to use the space, and that's where all the pipes currently arrive.

 

[D_Hailsham]

Thanks for the link for the heating assessment tool. I went and measured all the rooms, and had to divide the house into 4 areas, which I could then treat as semi-detached. The calculations added up to 29.92 kwh, so 30kwh looks to be spot on!
Why measure the rooms? The whole idea is that you just measure the size of the heated space. You must have a strange shaped house!

A semi detached only provides for one unexposed wall. If you need 4 areas, some of them must have had two or three unexposed walls. Think of a Battenberg cake.

Did you remember that you only need to allow the 2kW addition for hot water only once?

The system has a pumped heating circuit, and a pumped hot water circuit.

But it could still have a mixture of one pipe and two pipe heating systems. This shows the difference!

View media item 17739

 

[Chris43]

Thanks,
Yes, the house is a bit strange shaped, the result of at least two sets of extensions since the house was built in 1907. I put the walls as single thickness, although in fact we have, strangely, cavity wall up to downstairs window level and then single brick from there to the roof in the old part of the house. These are then covered in peppledash. And yes, not all of the 4 sections I broke the house up into hav 3 outside walls, in fact only 2, the 2 biggest. The others have 2 and 1 respectively. It is a sort of L shaped with a few other lumps.

I actually allowed 3000 for the water heating. And it is a single pipe system, not quite sure why there are 3 water pipes plus 1 gas going into the boiler......

Regards
Chris

 

[transam]

35 KW boiler Hmm LLH ?? I think some manus Vaillant ( maybe ?) would recommend a LLH on there single 45kw boilers ? if I remember correctly !

O.P why not discreetly contact the manu's & enquire as to what they recommemd ! In your original post U stated sump pump / that would be a shunt pump ?

 

[Mrmethane]

Hello

From what I can gather is that you are re-newing your boiler and retro fitting it to your old system, I could be wrong but I will push on as though I am not.
You have two problems. 1) Dirt and possibly sludge within your old system, this can only be dealt with by cleaning it with possibly removing the radiators to clean out any sludge present.
2) You want to maximise the efficiency of your new condensing boiler and wonder if the installation of a low loss header will do that.

I am not familier with your appliance but here goes. Condensing boilers work best when the return temperature is, has stated before low, i.e below a certain temperature possibly 55C. Radiators are tested to EN standard 442 or something and that is with a flow temperature of 75 a return of 65 and a room temperature of 20 degrees C. Thats how we know which radiator to choose to give us the right amount of heat output at a room temperature of 20 degrees. As you can see if your system is balanced to meet this criteria and insulation levels are good the water coming back to your boiler will be too hot to allow it to condense correctly, reducing efficiency. Your heating engineer will have to balance your system to give you a lower return temperature, the difference between the flow and return temperatures is called the delta T, you need at least 20 degrees delta T.
Now, your appliance will have a designed flow rate through it and your system will also have a designed flow rate through it to meet this new delta T, these two flow rates may not be the same, the low loss header provides a hydraulic separation allowing these two flow rates to exist without damaging your appliance and maximising it's efficiency. Thats of course if your heating guy gets it all right.

Hope this helps

 

[Chris43]

Thanks, a good idea. The email is sent!

And yes, my bad, shunt pump indeed it is.

 

[Chris43]

Thanks, MrMethane, and gday!

In my case, the boiler will be new but the pipes and radiators are old. None of the guys who have come to offer solutions have been very interested in the heating system as such. They can see the iron pipes, and accept my statement that the previous boiler got he house to an adequate temperature. But I can't imagine they can have any idea of the flow rate through it. All tenderers have quoted for complete flush, including in one case, different flushing chemicals for the copper based part of the system and the iron part.

So should I assume therefore that the LL header is really a safeguard because of the unknown flow rate in the heating system.

In which case, shouldn't it be best practice to include one whenever a new condensing boiler is being attached to an existing (and therefore potentially unknown heating system?

All I know, and the evidence is clear from the replies to date, that it isn;t a commonly accepted practice for domestic situations.

Hmmm....comments anyone?