Convert warm air district heating system to water based rads

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I have a flat in a high rise council block. The block has a boiler in the basement which pumps hot water to each flat. Each flat has something similar to a car radiator and a fan which uses this hot water to heat air which is blasted to a couple of the rooms (but unfortunately, not all of them).
I want to convert this water/air heat exchanger to a water/water one so I can heat all of the rooms using radiators. I know of other installations where this has been done in every flat in the block by the local authority using plate heat exchangers like this one...
http://www.alpha-innovation.co.uk/c...ing Units Installation Instructions 06.10.pdf

I'm not sure if I can upgrade my flat on it's own or whether this must be done to the whole building by the local authority.

In theory, it should be a fairly simple swap. My initial concerns are...
1) Would my plate heat exchanger block up with sludge from the existing primary circuit which I have no control over? I thought of perhaps adding a magnetic filter to control this.
2) Would the existing primary circuit have a sufficient temp to heat rads?
 
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In theory, it should be a fairly simple swap. My initial concerns are...
1) Would my plate heat exchanger block up with sludge from the existing primary circuit which I have no control over? I thought of perhaps adding a magnetic filter to control this.
2) Would the existing primary circuit have a sufficient temp to heat rads?

1) Probably; it depends on the condition of the district heating system, which you have no control over. You'd have to have strainers upstream and plan on cleaning them regularly. Forget magnetic filters, unless they're part of a strainer. This is exactly what happened on my first encounters with plate heat exchangers on a district heating system. This arrangement is quite common in office blocks where the services are provided by the landlords and the Heating, Ventilating & AC for each floor are provided by the tenants.

2) You'd need the primary and secondary design F&R temperatures and flow rates; the makers would size the PHX from that.

You also need to consider the resistance of the PHX, which is high compared with an air heater battery. You'd need to involve the owners of the district heating system in your plans.

I enquired about a tube-in-shell heat exchanger to replace the filing cabinet sized PHX that had failed. I was told it would be 40' long and a huge amount of copper tube would be required. I abandoned that idea.
 
Hi Onetap
Thx for your response.

Yes, I probably would use both strainer and a magnetic filter such as Fernox TF1. Belt and braces approach, just in case.

I considered the resistance of the PHX but I thought it wouldn't be an issue since there are 100 flats in the building. I'm assuming there is a single primary circuit around the building and my current air heat exchanger is simply connected across the flow and return in parallel with the other 99 flats. I'm thinking resistance through my little PHX would be offset by the other flats' existing air heat exchangers.

Let me know if I've got this wrong since I've no experience of district heating apart from what I've got in my flat.

I'd like to avoid involving the local authority who manage the main district heating system if poss as I doubt they'll be very interested my plans to upgrade the heating in my flat.

The makers of the Alpha unit I mentioned have warnings that 'An automatic system by-pass must always be fitted'. I'm thinking they would just want me to fit a pressure valve so that flow by-passes around the PHX if it becomes blocked. Does this sound right to you?
 
I'd like to avoid involving the local authority who manage the main district heating system if poss as I doubt they'll be very interested my plans to upgrade the heating in my flat.

You have to involve them as any interference with the common service of the building without their approval will be in breach of your lease.
 
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YOU MUST INVOLVE the operator of the district scheme
many large scale district schemes work at quite high pressures and are classed as MPHW (Medium pressure hot water) and often operate at above atmospheric temperatures (135'c + ) clearly you would need to know the temperature and pressure of the primary circuit as fitting a plastic filter such as the TF1 or other inappropriate fittings at elevated temperatures could be lethal!! ;)
 
Fair point. I'd rather not do this myself anyway. The local auth have always told me that maintenance of the current installation in my flat is my responsibility so I've not discussed it any further with them.
I've asked a couple of local plumbers about upgrading it but they've just pointed me towards copper tanks and immersion heaters.

I've tried to find a company who do this sort of thing but haven't had much luck. Does anybody know who I could speak to who would have experience with installing these and perhaps solve my problem.
 
I've tried to find a company who do this sort of thing but haven't had much luck. Does anybody know who I could speak to who would have experience with installing these and perhaps solve my problem.

What area it is in? Is the heat supply metered?

There is no 'standard' way of doing the district heating so any guidance you get here has to be based on assumptions.

The commonest arrangement would involve an isolating valve and a regulating valve, on the landlord's heating mains, for each flat. The regulating valve on those flats nearer the pump would be partially closed in order to make the circuit hydraulic resistance through each flat equal; this ensures that each flat gets an equal flow rate. If you were to install a PHX with more resistance, you'd have to get access to the regulating valve to open it up more. The regulating valve should be inaccessible to the tenants since altering the setting would screw up the flow rates for all the other 99 flats. In short, the landlord/local authority has to be involved.

You could also anticipate that the isolating & regulating valves haven't been moved in years, don't work and/or will start leaking once you use them.

It would be unusual for it to be a MPHW system, since the insurance & inspection costs are much greater; that does not mean that it isn't MPHW.
 
The flat is in central London.

The supply isn't metered which means that I have a hefty heating bill as part of my annual service charge whether I use it or not. It's one of the reasons why I'm trying to use the district heating rather than installing electric storage heaters which would be much simpler.

It's on the top floor of the building so I'd expect there's not much left to open on the regulating valve.

I'll speak to the local auth and see if they will help.
 

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